Infinite loading screen You are able to login, but can't get past the loading screen, no matter how long you wait.
Contact support and have them reset your avatar.
You can contact support on Discord by posting a ticket on the #support channel. You will need to be verified there (#get-verified channel).
Or you can contact them using the support page: https://3dxchat.com/support/
Missing mouse cursor Your mouse cursor is nowhere to be found in game.
There is a shortcut t