Please do a full **clean** re-install:
- move any valued save games elsewhere
- "uninstall" in Steam-EU4
- manually delete both the Steam/SteamApps/common/EU4 AND Documents/Paradox Interactive/EU4 folders
- re-install game in Steam, run a Steam Verify when done.
- add EU4.exe to the exceptions list of your antivirus app; ESPECIALLY if you have Windows Defender, add it to the Ransomware "Apps Allowed Through" list.
- start the game with no mods active and test
In particular make sure there are no files or folders left under either the Steam EU4 or Documents EU4 locations, before installing again.