Oh wow, after further testing, this is a display bug.
What you see in the schedules display, is the list of schedules for ALL switches. In other words, each individual plug schedule is still intact. It’s just that it doesn’t say which item belongs to which plug!
C’mon Wyze. It’s bad enough that the user has to do the testing for your app. That we have to buy in (pay for the product) to do your (testing) job, is not good.
Edit - Note this bug only appears when you group plugs.