Since a few weeks I have this problem.
There are in the colomn where the filter options are multiple identical filter options.
As you can see at:
https://www.sikumuseum.nl/en/6-super-series
Not with one option, but with all!
Is this a known error?
Steps so far:
- cleared cache
- reindexed features list
- looked for newest version (I use 3.7.0)