When a MR has finished with the selected
squash commits and
delete source branch. The source branch does not delete. There is a spinning circle indicating that something is happening.
Using Firefox Network Inspector I found a couple errors.
Source map error: Error: JSON.parse: unexpected character at line 1 column 1 of the JSON data Resource URL: https://my-server.com/assets/webpack/main.5565962b.chunk.js Source Map URL: main.5565962b.chunk.js.map
Uncaught (in promise) Error: SIMPLE_POLL_TIMEOUT o https://my-server.com/assets/webpack/pages.projects.merge_requests.show.505b2803.chunk.js:4 handleRemoveBranchPolling https://my-server.com/assets/webpack/pages.projects.merge_requests.show.505b2803.chunk.js:4
If you refresh the page the MR is completed and you have an option to delete source branch. When selecting from this screen the source branch does delete.