Once I drag and drop the videos down into the Media Pool, they disappear from the source folder, at least I can't see them. Blackmagic must know this happens because they do have a 'Re-link clips' line item in the drop down menu I get when I right click on the offending clip. Both 8 core Ryzens, same video card on each. I'm having this happen on two desktop computers that I have DR17 on. Then I sheepishly go back to the Edit page and dutifully delete at just before the Media Offline message appears. I move the timeline cursor (whatever it's called) towards the end and inevitably Media Offline appears and if I just ignore that and go to the Deliver page, the clip won't render 'FAIL!!' I'm currently (as of right now) dragging a clip to the timeline knowing I'll have to delete the last two seconds. But a lame system hasn't been pointed to as the culprit on any vY'Tub I watched. I'm not using more than 12 GB ram during any processing. I guess it could be a hardware issue although I do have 48 GB ram, a Ryzen 3700x and the required minimum 4 GB VRAM.

I just drag a clip into the timeline (just one clip) and the ending 2 seconds, 99% of the time show, in red, 'Media Offline'. Unless that happens by default, I haven't chosen any resolving.

Davinci resolve 16 media offline