I can't stay logged in

[SinisterBumFacedCat]

Previously when I was signing in with my nickname I could stay logged in pretty much all the time.

Since the change over to signing in with my email address I am unable to stay logged in, and have to log several times. Tonight I posted something, clicked a link, and then 30 seconds later came back to the thread and it already logged me out. I have the keep me logged in ticked every time but it makes no difference. I'm using an iPhone.