All preview renders are dissapearing, all clips are red, not green or yellow

I am working with the current PP 2024.

I opened my project after following a tutorial suggestion and the entire project appeared unrendered eg red instead of green or even yellow. My clips are about 50% direct from file (Quicktime Prores422) but I did switch to "ingest" mode at some point. Most imported clips are at 1080p for a 1080p project at native resolution without proxies but all clips imported as yellow and remained green if rendered even once.... until now.

So I went and rendered everything... (45min sequence taking an hour) and all was good. But after shutting the machine down, the sequence was red again when reopened the next morning.

I am working on a Win 11 laptop with two NVMe drives... (C: as OS and Apps, and 😧 just files) and I have 64gb RAM with 58gb for Adobe to play with. I moved the scratch disk volume from the default location (same as project to a dedicated folder on C:). Curiously I got a warning about "low memory" after the second time it went down, which baffled me. I went into the settings and switched the mercury playback to include CUDA. Suddenly everything is yellow not red. But what about all the stuff that was rendered, including effects? What about the clips that were ingested?