Gitlab created branch deleted via git, now issue is 500

this is what I have done.
Created issue. In issue page, created branch.
Realised that branch was created from master when I wanted it created from release branch.
On gitlab server, logged on, went to repository and run git branch -D name.
Went back to issue in gitlab, received 500 response.

So a few questions.
How do I repair the issue?
For creating the branch, I can go to branches and create a branch which allows me to say where to branch from. Is there a better way?
Also, I noticed in project settings I can set the default branch but that only allows a single branch and if the team is working on a release and maintenance then I will want branches to start from different parents.

Just to update. If I created a new issue and created a branch for that then that updated the branch list and the previous issues were now available.
So it appears that branches deleted outside of gitlab need to be forced to reread the database.