The fix for me was after restarting the PC (since Apex has to be closed),
Reinstall EasyAntiCheat then reinstall Steam
1.) Reinstall Easy AntiCheat: file located on Steamapps\common\Apex Legends\EasyAntiCheat
Run the EasyAntiCheat_Setup.exe
Select Apex Legends > Install
Then press "Repair service"
2.) With Steam closed, download Steam from their site. Delete all the files and folders in the Steam folder except SteamApps.
Cut and paste that SteamApps folder elsewhere since the Steam folder has to be empty to reinstall.
Once you log into Steam close it, then cut and paste the SteamApps folder where Apex was downloaded to back into the Steam folder.
Launch Steam, click into Apex, and when it says Choose a drive, select the location where the game is installed and it should auto-detect that it's installed. Then Cancel out of the installation window.
TL;DR, crux of the issue may be EasyAntiCheat and/or a corrupt Steam install.
Spoke too soon, the issue is back again...
yeah tried the same with EAC, uninstalling, worked the first time - buit didnt actual load into a game, only the lobby. Played a game and quit and it's still there in steam and the processes.
