We’re investigating this issue, in the meantime I recommend you to do a temporary fix.
Before you launch the game, please make a copy of mod-status.json file, this can be found here:
C:\Users\YOUR_WINDOWS_USERNAME\Games\Age of Empires 2 DE\YOUR_STEAM_ID\mods\mod-status.json
You should also copy your mods to /local.
Mods default folder is: C:\Users\YOUR_WINDOWS_USERNAME\Games\Age of Empires 2 DE\YOUR_STEAM_ID\mods\subscribed
Copy the folders found there in:
C:\Users\YOUR_WINDOWS_USERNAME\Games\Age of Empires 2 DE\YOUR_STEAM_ID\mods\local