31 May 2021: APP 1.083-beta2 has been released ! APP 1.083 stable will follow soon afterwards. It includes a completely new Star Reducer Tool, New File Saver Module, Improved Comet registration and much more, check the release notes here!
Only darks and bias
darks bias flats
My guess would be that, since it only happens when using the hyperstar, something is not going right while taking the flats. There must be some difference between the time you take the lights and the flats, apparently the vignetting is stronger when taking a flat frame. Very tricky to pinpoint what it is exactly without hardware access.
I've taken my flats the same way since I got the HS and it has only become an issue recently. I can't imaging why it's all of a sudden not working
Strange, no difference at all in the way you take the flats either? Did you use different bias frames or a different APP version (not that that would be the cause, bu just probing where there are differences 🙂 ).
Try doing your flats by imaging clear sky - before your imaging session. I'm not sure about hyper star but I saw once that putting a t-shirt at the end of the dew shield yielded bad results. I put the t-shirt right at the front of the telescope but the last time I did my flats I used the clear sky approach . Also, image train changes may result in bad images because of thinks like stray light. Did you change any image train components?