I once added three interests and now they are stuck. The app doesn't add any new interests that I enter. When I remove the existing three and enter a new bunch of keywords, it won't work either.
To fix this issue download the latest Feeld version. Before adding any new Interest or Desire tags, first, remove all your existing tags. Then add back everything in one go, remembering to separate each tag by a comma. Let me know if it works!