I've done this (so we'll see about future purchases) but it keeps creating a new internal transfer for me with all the products in it, even though I cancel the reservation and the transfer each time. Any idea?

I'll make the necessary checks and get back to you.

However, with the "Take from Stock" supply method, my purchase orders are no longer automatically updated with the necessary products. When I try on my Odoo test with the same parameters but "Trigger Another Rule", my purchase orders update automatically.

That is correct, if you set 'take from stock' the route wouldn't trigger reorder. The reorder would be triggered by replenishments

The reason for suggesting the change was to validate if the internal transfers with all products were being triggered by the route. And my understanding of your question

>>>It seems to me that the problem lies with my rule, and more specifically with "When products are needed in ...".<<<

It seems the cause of issue is by stocks being available in Input location and the push rule set on this location creates the internal transfer.

Could you be more specific about the explanation below? What is the difference?

>>>That is correct, if you set 'take from stock' the route wouldn't trigger reorder. The reorder would be triggered by replenishments<<<

There are 2 ways to trigger a reorder (buy or manufacture)

1. Is by using the route. If stock is unavailable at the source location then trigger another rule. 

In this scenario the status of picking would be ‘waiting on another operation’

Supply method on the rule would need to be set to trigger another rule or take from stock and if unavailable trigger another rule

2. Reorder through replenishment, this would consider the min, max and qty multiple for a product to trigger reorder. Trigger can be manual or auto.

In this scenario the picking would be in ‘Waiting’ status

To use this process supply method on the rule needs to be set to take from stock.

Hope this helps to clarify.

Thank you for this clear explanation.

At the moment my picking is "Waiting" and not "Waiting for another operation".

What you are suggesting is that I change the supply method from "Trigger Another Rule" to "Take From Stock"? In that case, I wouldn't potentially have the bug I have?

However, I noticed that my purchase requests were no longer updated automatically (even if there were minimum and maximum quantities defined). Is this possible?

In any case, I'm going to try what you've suggested again.

1. The issue that you facing about the internal transfer being created with multiple products and qty not in line with 2nd step of receipt operation — I believe that has to do with stock mismatch at input location due to cancellation of prior internal transfers. 

Do validate if that issue has been identified and rectified?

2. Purchase requests being created by routes or by replenishment rules should not have an impact on the above issue. So depending on your business needs you can set it to routes creating purchase or replenishment (min and max) creating purchase. 

I'll give it a try and let you know. Thank you

Initial problem with products not fully transferred: solved when I switch to "Take From Stock".

But since I've been using this supply method, none of the replenishment rules have worked:
- My minimum/maximum orders no longer trigger a purchase.
- An order with a product at 0 stock no longer requires a purchase of this product

Good that your initial problem is resolved.

I would check the triggers & routes that have been set on products in replenishment.

It is likely trigger is set to manual, hence RFQ isn’t automatically triggered.

As I understand it, the problem is the Supply Method that we've changed. Because the purchasing rule says this:

https://i.imgur.com/0qkGH4S.png
When products are needed in WH/IN, a request for quotation is created to fulfill the need.
Note: This rule will be used in combination with the rules of the reception route(s)

It is therefore triggered by another rule in the receiving area, namely this rule:
https://i.imgur.com/cTrl1Ju.png

If I use the "Take From Stock" Supply Method, this causes problems because it doesn't trigger my "Buy" rule. However, if I use "Trigger Another Rule", it works because it adds this condition:
"A need is created in WH/IN and a rule will be triggered to fulfill it."

I've tried but it doesn't work. The problem is with the "Pull" rule:
When products are needed in WH/Stock, Internal transfers are created from WH/IN to fulfill the need.

It should not create an internal transfer. It should trigger the "Buy" rule, and when products arrive in "IN", it's the "Push" rule that creates the internal transfer.

Routes and rules can be set back to defaults, as I understand this isn’t the cause of the issue — mismatch in product and qty in the internal transfer operation.

Are you able to validate if WH/ Input location has stock that tally (physical Vs in Odoo)?

I believe by canceling previous transfer operations Odoo continues to count stock at this location awaiting transfer to WH/Stock

Beware that there may be a misunderstanding. What Odoo does is create an internal transfer between my reception and my stock with hundreds of products reserved but not in stock (the transfer is often "Waiting"). As soon as I delete the transfer or backorder, it recreates a new transfer for me. In my opinion because of the part "When products are needed in WH/Stock, Internal transfers are created from WH/IN to fulfill the need."

So there's no question of physical stock.

Yes, I tend to agree that internal transfers are created when stock are needed in Wh/stock however I understand it is disproportionate to your outstanding PO receipts.

If they were in line with receipts the issue wouldn’t have risen in the 1st place.

While the transfer is ‘waiting’ you can ‘check availability’ to validate availability and make reservation 

My suspicion is that in the past receipt operations have been validated while internal transfers have been cancelled or deleted. The system still believes that the products are still needed in WH/Stock, hence creating the internal transfer.

Another way to cross check is to check product availability in WH/Input location 

And how can I solve this problem? So that the system no longer thinks that products are necessary?
Because that's a big problem

@Jaideep any idea?

Maybe there are POs which aren't completely received basically open backorders.

Are you able to validate if these products aren't already in the WH/Input location?