I had the same issues with a PB max tow. Took it to Gary Yeomans Palm Bay FL (outstanding experience for anyone in that area). They tried to tighten and the bolt broke when they torqued it down. They replaced both axels under warranty in a few hours. Heads up, they don’t keep the parts in stock...
Wondering what engine configuration you have. Im curious if your setup works on the Powerboost. I read on the Thinkware website, the power adapter T harness isn't for hybrids.