My lightroom (PC) and lr mobile (android) keeps "signing me out". Nearly every time I start lightroom I have to resign in. That is very annoying especially on my mobile. I found this solution for the desktop version https://forums.adobe.com/message/6374813#6374813 and I would really like to try that one, but when I click on lr mobile sign in, the opening popup stays white after the short "connecting..." message disappears. So I cannot even sign in.
I do really ask myself, why I am paying the subscription, when it won't work properly..
Try removing LR mobile from your mobile and then install it again, after doing this try the steps mentioned in the other forum