I think I found the issue. The other day after a reboot I noticed that it was much more stable than ever before. In nvidia-smi the order of the GPUs had flipped so that the RTX was GPU0, and the 1080 was GPU1 (the 1080 is in the first PCIe slot and RTX in slot 3).
I had read before that nvidia-smi usually allocates GPU0 by speed, not by PCIe location, so it looked like this hadn’t happened properly after the driver install/reinstalls. I don’t know why it randomly decided to switch them and why after so many reboots it chose that now was the right time to do it, but i’m glad it did since everything is fine now. Thanks for your help though!