Minecraft PE isn't letting me sign in

I've been had the game downloaded, when I wasn't at my ps4 I played on my phone. Until the last update I wasn't able to log in back to my account. When I press the "sign in for free" button, it would open up a minecraft page but it would stay black, it would then close itself like it remembered me and logged me back in. When minecraft loads back im still not signed in. Please help me

:)