I just replaced a dumb dimmer switch with the Tapo S500D. It's controlling a dimmable 12v transformer.

it worked great with the dumb dimmer switch and worked with the smart dimmer switch but a few hours after installing the Tapo S500D, it stopped turning on the transformer. I tried checking all connections and each time the smart switch would work again for a few hours and then stop working. I noticed that the transformer wouldn't turn on if the Tapo S500D was set to low brightness but would work fine if the brightness is medium or high. The weird thing is, after a few hours the Tapo S500D stops turning the transformer on.

I've tried checking the connections multiple times, it works fine then stops working a few hours later.
 

I've disabled the gradual on/off setting
 

I've tried turning off the breaker and it doesn't seem to reset the switch. I need to disconnect it to get it to work again.

Do I have a bad switch?  Any ideas?