Certainly a strange one, and would be good to know what happens visually. I'm not familiar with Backyard EOS - is that what you normally use to guide in? Is there any other software that you could use to verify drift. Is there definitely no tracking at all turned on? (another reason to use a different program possibly).
Drift aligning with a camera is a great way to got aligned once you have it sorted, so worth persevering (not that helps much right now
)