Something is still blocking the trainer on your side.
Even though you deactivate AV or firewall some might still have a process running in the background.
Trainer downloaded and ran fine here on Win 10 vanilla with Win Defender and Win Firewall enabled.
Did you edit this value manually via the Editor of the trainer?
It seems that I solved this by augmenting my exp point to ""0" before the next level". After this, my level doesn't reset after a battle.