Adobe Rush 2.5 wont import clips -- red screen no excalamation point

Hello,

I am suddenly finding that ALL of my clips (mp4s from a GoPro) are not recognized by the application. This includes clips that I have previously imported and edited into videos. When i (for example) try to create a new project and navigate to the external drive where my media is stored, the clip names and locations are there, but the application displays a red screen without an exclamation point instead of a thumbnail. When I select the file, it loads into a timeline as audio only. These video files are not corrupted -- they import into Premiere Pro just fine, play in preview andon other video apps, etc. What the heck is going on?

I have uninstalled and reinstalled the application, and i've tried previous versions, I've restarted, logged out and logged back in, etc., and I am extremely frustrated.