Correct! I could have elaborated a little better.  Each of our custom forms has both an Issue and Project version of the form, we have to keep these 2 forms in parity.  The issue form is involved in the request, when we convert to project we use the corresponding project form. The best way for us to...

Our requests come in as issues and we use templates to attach the correct custom form when converting from issue to project.  If we don't use templates or don't manually apply the custom form the form does not get attached in my experience.  This has always been the behavior to the best of my knowle...

+1 to this response I was given the same instructions for a different proof issue and it worked in our case.

Was this issue fixed?  I am not able to find it on the known issues page for Adobe Workfront Proof https://experienceleague.adobe.com/docs/workfront-known-issues/issues/proof/workfrontproof.html?lang=en  

I do not believe so.  I'm trying to imagine what a form with 500 fields might look like - probably very busy!  At that point it would almost make sense from a functional perspective to have different forms I guess.

In the custom form that you have open there are currently 100 fields being used - the maximum amount of possible fields is 500

Do they have access to the items they are clicking on?  Could it be a permissions issue?

I think this is the dashboard that you're talking about - I use it and it's very helpful   https://experienceleaguecommunities.adobe.com/t5/workfront-discussions/released-system-admin-maintenance-dashboard/td-p/550997

If you assign a layout template you should be able to do this.   Customize what users see -> Project change to  Customize what users see -> Task

We stick to ProofHQ proofs for everything because it's really confusing to most everyone having both document proofs and PHQ proofs in the same environment.  It's not a problem anymore because everyone is aware, but for a time I wanted to completely disable document proofs.