Players who have recently installed/reinstalled the game don’t have the latest version of the game (they have V.100.15.59076.0, but it should be V.100.15.59076.0 P1). And thus they cannot see any rooms in the multiplayer lobby.
To fix this, you need to manually update DataPatch
- copy DataPatch
- paste it to User/games/Age of Empires 3 DE/XXXXXXX/
Unfortunately I cannot upload the DataPatch files here, you can find them in Age of Empires Discord - iii-tech-support Channel Age of Empires
Or, you just syncronzie your windows time 
What I did that last 2 times when having problems with updates is start the game let all the intro videos play (don’t press any buttons) and once they are done and in the main menu wait a few minutes before doing anything and it worked in getting the latest update installed.
does not solve the problem. Tested with few people. Only updating the DataPatch will do.
It works perfectly fine.
Even when windows sais " Tiem is synchronized " jsut disable the setting, and enable it again.
