3 way wiring blowing lzw31

Wanted to ping the group here to see if anyone has insight into what’s going on; pretty new to smart switches but have been replacing old dimmers with LZW31 and GE aux switch. They all work okay except this one:

The layout is a 3 way with line and load in separate boxes and neutrals present
It’s controlling 6 recessed lights, ~7w each

When I first installed it it was working fine for a week. Two days ago though turning it on started giving this horrible humming noise, and the switch would become unresponsive to smartthings. Then it stopped working altogether;

Strangely when I replaced the switch, it powered on fine, but as soon as I tried to increase brightness the new switch also stopped working altogether. I also tried a GE switch without neutral and switched the confirmation of the main and aux switches, and the GE switch was able to get the lights turned on briefly (1 min or so) but then also died.

I’m assuming there is power going over the traveler? Or something strange, but not sure why it was working for a bit before seeing this behavior. I have been switching other lights around the house without issue. Any thoughts?