Can't see or filter by MR tags anymore on Create & Manage site

What happened?

I used to filter and modify tasks of a challenge based on set MR tags, but this doesn't work anymore. I can still see a column "Tags", but it's empty for all entries and adding a filter doesn't do anything. If I export the list or open a single task I can see that the tags are still there.

I've checked it with different challenges, to see if it has something to do with this particular challenge, but it didn't;

Steps to reproduce

edit a task and add a MR Tag

go to the corresponding Create & Manage site of the challenge

the column "Tags" doesn't show the added MR Tag and when selecting "Filter by tags..." and entering an arbitrary filter it doesn't change anything

Environment

Opera 131.0.5877.55 / Firefox 150.0.3; Windows 11 Pro 25H2 / Ubuntu 24.04 LTS

Additional information

No response

Start by reproducing the issue from the Create & Manage site: add an MR tag to a task, then inspect how the Tags column and “Filter by tags...” control obtain their data. Done means existing MR tags appear in the column and filtering changes the displayed tasks, while exports and single-task views remain correct.