EDIT (13 Jan, 15:23 GMT+0): iOS update available now. Please update your game to fix this issue!
EDIT (12 Jan, 18:30 GMT+0): We have now released an update for Android which should fix this issue, please update your game! The iOS update will be available as soon as Apple approves it - hopefully within a couple of days.
There is currently a known issue with Alliance Chat not showing older messages (chat history disappearing). We are currently investigating the issue here and hope to get it resolved as soon as possible.
Our apologies for any inconvenience caused by this issue!