Not sure what the issue is with the wanted hereos. This happens everyday. Its also annoying to be playing and when destroying an enemy it says missing hero. If you want people to play these bugs need to be fixed.
Its not a bug.
When it says “Hero missing” it means you dont have heros of all the colors in your team.
Making combos with tiles of the color that isnt present results in that message.
Fledoble gave the answer. Thread closed.