It sounds like the media may be going offline. Where is your media located? ...local, server, hard drive... etc. If it;s a hard drive or server, ids it possible that the location itself is going offline and back on? Otherwise it may be a media cache problem, in which case you can delete those and re-generate. I (or someone else) can send instructions for that if needed. There may be other possibilities to explore too, but let's start here.
Media is not offline. I'm getting the dreaded yellow "Media Pending" And when I first open the project It works for a few seconds to a minute like nothing is wrong. The clips play in trim and the timeline works then
the clips suddenly stop and turn into the yellow Media Pending. Then the timeline freezes.
Local Hard drive