The first of these updates adds a limit to
background activity unless the watch is charging.
Not exact matches
There is no reason I can think of why putting it in and out of sleep should cause a freeze — that would be bad design,
unless it is stopping a
background activity and confusing the Kindle then.
Next, Android P for Wear OS limits
background activity to an enormous degree by shutting down all apps running in the
background,
unless your watch is on a charger.