Hi,

Right now the Validate Inventory button is visible only for the Manager level users in the Inventory. 

If you want that button visible for the inventory users, what you have to do is that, either you can add the user to the group Inventory/Manager, I think this is not a good one, so follow the next one.

Activate the developer mode and navigate to the Inventory adjustment form view from the admin login.  Then click on the lady debugger button and click on the Edit form view .

Now you will get a pop up, in that in the Architecture page, you can see the view.

Then check the button  Validate Inventory , along with it you can see the group attribute.  Just remove the group attribute from there and save it. This will make the button visible for the inventory users also.

Either you can remove the group attribute from the button or give the group as stock.group_stock_user instead of stock.group_stock_manager

Thanks