I'm not sure why but I can suggest a theory I have.
I'm using V38 Go beta on a Honor 7S with Oreo 8.1 and apart from a message" This device is not supported so calls made not work correctly" everything works fine, but very slowly.
My theory is both my devices have had several Google app/ Google suite app updates in the past few days and since those updates, every Google owned app has been horrifically slow with many stupid lockups.
Gmail, Google, Google dialer, drive and photos have all been doing this on both my device since mid week, to the point I factory reset one device yesterday and everything was ok until the Google suite apps all updated via Google play.
This morning my Nokia has horrible slow downs and lock ups on all the Google apps again, so I think it's something Google have done or are doing.
I'm not having any issues with other apps like Facebook lite, messenger slide for Reddit, XDA ect.
Sorry if that's considered off topic but it's happening so I thought It may be relevant.