Problem statement:
Recently while working on issue in Dynamics 365, found that all the lookup fields included in a stage in the Business process flow are locked out and not able to edit and we were not able to move to next stage since these fields are mandatory. We modified to show the stage owner properly, but even though when that stage owner logged in these lookup fields used in the Business process flow are locked.
Solution:
Give Append and AppendTo privileges to the other entity so that these fields would be unlocked and at the same time you need to give read privileges on the related entity so that user could see this lookup field without any permission issue, you need to give write privileges too in order to edit and write data in to that field.
Hope this helps someone…
Cheers,
PMDY