D365FO (on-prem)
Recently we discovered that in our PROD env there have been a small number of posting with a non existent financial Dimension.
All those posting occurred around 3 months ago, and are all related to Purchase orders tied to a specific ProjId.

We tried to replicate the issue without success, and I'm starting to think that it's due to some customization that now has already been fixed.
Usually we fix wrong (but existing) financial dimension posting with a general journal, but in this case we can't because the original one does not exist and it won't let me put that dimension in, throwing the following error.

Is there a way to fix this situation?
Any hint on will be appreciated.
Thanks