Denodan,
Using my dashboard, I see the following graph for my UV. While I have no way to validate the values, The UV readings appear to follow the sun exposure. On several days we had quite a bit of cloud cover so I would expect the readings to be lower than when we have full sunshine. This past week we've had a mix of open sky and clouds so the variations seem to be acceptable.
Good luck on getting your unit working as it should be. It looks like Bloomsky support really does want to help to get their units working correctly but, as a new company, I suspect they are overwhelmed with support calls and initial equipment setup issues. I guess I was one of the fortunate ones in that my unit seems to be working (so far) as it should.