In Project Navigator 12.1my User Constraints Format (UCF), EDIF (EDN), or NGC source file seems to get lost (i.e. it disappeared from my project).
This happens if I try to add a second UCF file or if I remove the original source and try to add it again. When it does not show up, I try to add the the file again and I get an error telling me that it already exists so I cant add it.
We have seen this problem on the SECOND (and subsequent) adds of UCF, EDN and NGC sources within a given session (not project) of Project Navigator. Generally, a user is able to successfully add at least one UCF or NGC/EDIF, and they see this problem after adding a second file of the same type or removing the file and adding it again.
The issue is that when the source file is added, it defaults to a View Association of "None" instead of "implementation" or "All". If you do not catch it during the Add Source step and change it to Implementation, it will be added, but not to the Implementation View, and thus you will not see it and it will not be used during Implementation.
To fix the problem, go to the Files tab. You should see the source file in question with the Association set to None. Change the association of the file to Implementation. It will then show up and be used.