I also noticed that and I also noticed that it starts to struggle when the workspace "tab" you're working in gets longer - it basically gets stuck at "Starting agent ...". I initially thought it must be a very big context that the model is struggling with but since since restarting the "app" and kill -9 fixes it, it suggests that it's a local issue. Strange.
Seems like capacity because it works a lot better late at night.
I don't see the same with the claude models in antigravity.