What you note is accurate. The reserved qty only changes on the pop up when the related delivery order reserves the qty. (tested on V17.0)

In case of multiple step delivery, when the product qty is finally reserved at WH/output location prior to validation of delivery order the reserved qty updates on the pop up.

This behaviour is consistent irrespective of the reservation method set on the pick, pack and delivery operations.

Couldn’t tell if it is intended behaviour or a bug.

However, from V17.2 the multi step routes have been changed to push rules, with these the reservation seems even more erratic and misleading.

- On the pop-up reservation qty is updated, but with the graph icon being in red color

- In the forecasting screen of the product the reservation isn't visible until the products have arrived at WH/Output location

- With the validation of each operation (pick & pack), the reserved qty count keeps adding the demand. i.e for example demand is 2 on SO, on validation of the pick it updates to 4 and on validation of Pack operation it updates to 6!

With the forecast report not updating the reservation with a SO until the product is reserved by WH/out (delivery operation), sure seems to be a bug.

If you are on enterprise edition, would encourage you to open a ticket with the odoo.com/help