Scheduling video in Sprout

Help! My intern and I are struggling to schedule an Instagram Reel and TikTok in Sprout. Whenever we do, the thumbnail is just a gray box. In the composer section, it’s just a gray box with a loading bar at the top. 

We have two seats in our account. Regardless of who uploads, we still get the gray boxes,

We’re trying to work through this with support but haven’t gotten far. Has anyone else encountered this problem?