this bug have been there ever since release of new chat ui, they never really cared to fix it. i guess that this new feature with screenshot share and clips people are starting to understand it and forces valve to fix the issue

I've had this same issue for two weeks.
It started happening after sharing a few gameplay clips using the new steam recording.

This blows, I can't share anything anymore after sending a couple clips to friends. What's the point of making clips if you can't even show them to anyone. Super frustrating.