When trying to connect to a realm, it endlessly displays the "connecting to the realm" screen.
Linked issues
duplicates 1
Comments 2

This appears to be a duplicate of REALMS-3075, which hasn't yet been resolved. If you have any additional information to provide regarding this issue, feel free to comment on the parent ticket. If you feel that this issue is affecting you, feel free to vote for the duplicated ticket, to give Mojang a basic idea of how many people are impacted by the problem. Just to further inform you, this will not determine how quickly the bug gets handled or fixed.
I also have this problem. Stuck on connecting to the realm screen ever since the update dropped.