This was slowly driving me insane over the past few weeks and there were no results when searching for it, so I’ll post it here for posterity.

I have a work profile set up through Shelter on one of my phones. Several weeks ago, I started noticing that a few times each week, I would be prompted for my PIN when trying to open a work app while the work profile was deactivated. Not once, but twice, once to activate the profile, and a second time to open the app itself. I checked every relevant setting I could think of, including “Use one lock” for work profile and device screen, and all the PIN prompts said were “For added security, enter your device PIN” with no further explanation.

Today, I snapped, stormed into the security settings, and disabled my device’s PIN entirely. I think the resulting catharsis let me finally think straight and realize in the next two minutes why. Sometimes, I’ll turn off the work profile. Sometimes, I’ll unlock with my fingerprint instead of my PIN. The two coincide a few times each week.

The PIN can unlock both the personal and work profiles. But the fingerprint only unlocks the personal profile. So if I unlock with only my fingerprint, when it comes time to unlock the work profile, it isn’t “sufficiently unlocked” and I need to enter the PIN. Why at the end of this process I still need to enter it again to open the app itself is beyond me.

TL;DR: Unlocking your phone with the PIN unlocks both personal and work profiles. The fingerprint only unlocks the personal profile.