I experience this as well; with random groups of (should be) switchable apps, in all profiles and multiple times per day.
For me, it always seems to happen when attempting to switch to the furthest right app within the app picker. Not every time but most, swiping over to that last app to the right freezes everything but Home & Back. It starts fine again after killed..until it doesn't.
I'll pay more attention and gather better info to share as an issue if need be.