Uploads to Screencast freeze, and logout attempts crash Capture

I'm on a Mac running Monterey 12.0.1 and Capture version 1.4.6.

I'm having two issues with Capture, and I have a feeling they're related to each other:

1. When I try to upload an image screenshot to Screencast, the progress bar doesn't move, the app becomes unresponsive, and I have to use Force Quit to get out of it.
2. When I click the gear icon and choose "Sign Out..." the app crashes.

I have logged into screencast.com in a browser and everything there seems fine. I'm able to log in and see all of my previously captured content. I only started having these problems when I updated my Mac to Big Sur. Before that, everything worked fine. I just now updated to Monterey hoping that would help, but I'm still having the same problems.

It seems like there's some kind of disconnect between Capture and Screencast, causing it to not upload and also not letting me sign out of the app.