Maybe I wasn't clear enough. Let me go more in-depth the steps I'm using to reproduce the issue and you could try them once more:
Step 1: Open the Windows 10 Enpass app.
Step 2: Lock and unlock the Surface again. Enpass should be locked and in the foreground. It starts to scan using Windows Hello, because the device was unlocked. Don't unlock the app.
Step 3: Switch to another app. Switch back to Enpass after a couple of minutes and see that the app has scanned using Windows Hello the whole time while in the background. Try again if it wasn't scanning after switching to it.
Step 1: Do the same as in Situation 1 Step 1.
Step 2: Switch to another app so that Enpass is not in the foreground.
Step 3: Lock and unlock the Surface again. Enpass should not be in the foreground after unlocking.
Step 4: After a couple of minutes, switch to Enpass and see that it has scanned using Windows Hello the whole time while in the background after unlocking the device. Try again if it wasn't scanning after switching to it.
In my option, Enpass app shouldn't be scanning using Windows Hello while locked and in the background. I know that the scanning stops after a long while (maybe because of failing to recognize faces), but the delay is way too long and has too big of a hit on my Surface's battery life if I forget to close Enpass before locking my Surface.
And to answer the question about any software I might have that could cause the freezing: I'm using Windows Defender as my antivirus software. I don't have any out of the ordinary apps running in the background that could cause unnecessary battery drain. Mainly Google Drive Sync and Backup, OneDrive and PushBullet.