Configure SAST in UI - Create Merge Request fails

A developer on my team was able to add SAST to an existing project following the documentation here: Configure SAST Manually

We were having some issues with reporting after setting that up, so we wanted to see how it would be configured if we used the GitLab UI, then compare the result. We followed the instructions for “Configure SAST in the UI” in that same article, immediately below Configure SAST Manually; we have GitLab Ultimate accounts so the option is available to us.

The first screen shows a button for SAST named “Enable”. I was expecting to see a “Configure” button according to the documentation, but I went ahead and chose Enable.

The next screen is quite simple, with several prefilled fields and a Create Merge Request button at the bottom. We followed the instructions, accepted all the defaults, and our project indeed has a .gitlab-ci.yml file. When we click Create Merge Request, we get the following generic error message…

An error occurred while creating the merge request.

Behind the scenes, we can see that it created a branch for us named “set-sast-config-1” from master, but there are no commits in the branch.

Has anyone run into this issue?

I am a relatively new GitLab user so I will not be surprised if I am overlooking something simple.