We applied the patch needed, The problem is the requester profile only has the one disallowed purchase class since we don't normally use purchase classes. There isn't an allowed purchase class to counteract. Therefore, when we apply the disallowed purchase class it disallows everything.
Edit: We could add an allowed purchase class but I'd like to avoid the transition period of PO20 error message if at all possible.
I would create a "EPIC EPIC" Purchasing Class on IC07 and change the items in question to that class on IC11.
Then use uploads to change all requesters to Validation Option 1 (Disallowed Purchase Classes) - not the 0 it defaults to.
Add Company and Major Minor EPIC EPIC
All other purchasing classes - even blank ones - will be allowed for the requester. It would only be items with EPIC EPIC on IC11 that the user would not be allowed to add.
We have one set for IT Equipment - screen shot attached.