We had that rattle in our '17 Challenger 37LX. No way I could drive more than a short time without losing my marbles listening to that! Took it back to CW. After a week, CW told me they needed to add some insulating material and re secure their loose microwave mounting. After another week, CW said they were still waiting for Thor authorization for the warranty work. Next day I called Thor, who had just approved it after receiving the request from CW the day before (when I called for the second time).
But it is fixed, and I'm happy about that.
I've also found some very unsatisfactory things when removing access panels, pulling the residential refrigerator out for Whirlpool to replace the non working fans, etc. They really have no pride in their workmanship at Thor's assembly line, they seem to just throw things together as fast as possible and go home. You'd think there would be some QC folks there who spot check things, at least, but based on comments in this forum, I don't think so.
USAF Veteran, Retired Security Professional
The only thing necessary for evil to prosper,
Is that good men do nothing.