As mentioned above, the auto-switching behaviour depends on the currently selected input in the WiiM.
This is my old test, but auto-switching from Optical input to Bluetooth did not work, while auto-switching from Line input to Bluetooth did.
In any case, simply disconnecting from Ultra on your tablet should not result in auto-switching.
Hi
I am very lazy and love features like auto-sensing.
So I will share the results of a little test I did on how the WiiM works with auto-sensing.
I investigated how the WiiM device works in three different states
During playback = audio signal is being input to WiiM
While idling = nothing is playing and the device is silent
On standby = the LED indicator is dimmed

= Worked fine

= Didn't work

= Switching after about 15 seconds, or unstable operation
[Auto re-switching/Yes] = Previous source playback continues and can be re-switched
[Auto re-switching/No ]...