Vault 2 no longer auto switching to optical input

I have a Vault 2. I run an optical (TOSLINK) cable from my TCL TV to the Vault 2 and have the Vault 2 configured to switch automatically to this optical input whenever it detects a signal. This has worked great in the past. I can be listening to Tidal on the Vault 2 but when I turn the TV on, it automatically stops playing Tidal and starts playing the audio from the TV. Until a couple weeks ago. I don't know what's changed. I still have the Vault 2 configured the same way. From the Blue Sound controller app on my iPhone, I go to Settings, Player, Customize Sources, Optical Input, and switch Auto Sense to On. But lately, the Vault 2 does not switch automatically to the TV audio. I have to go into the Blue Sound controller app on my phone, go into Optical Input and manually turn off Auto Sense and turn it back on. At that point the TV audio starts. Any idea what's going on? Thanks.