Help troubleshoot my Thule Rod Vault - is it me?

I have a 3-yr old Thule Rod Vault (the old Denver Outfitters design) mounted on the top of my Snugtop shell. It gets installed on the crossbars every June and comes off in October.

Today I noticed - for the 2nd time - that the upper half/threaded portion of one of the tube clamps was missing. If you have this product, you know that the bolt that holds the clamps and feet together sits upside down during use, and the entire rod vault must be removed and disassembled to check for tightness. If it works loose, it will allow that top clamp to come off. After this happened the first time, Thule warrantied the clamp and sent a new one. I rewatched a good video, cleaned all the bolts and put some Loctite on them. Fine for a season, until now.

I am starting to think I am doing something wrong during installation. It is the same part that has flown off both times, so maybe something with weird stresses as the truck torques and twists? The rear clamp has been fine.

For what it's worth, the two parallel rod tubes also become uneven after driving for a few days. I am thinking this product is not so great. Installed a 3rd clamp today and secured it with a rubber strap for extra security. One should not have to do that for such an expensive product.... Curious to see if anyone else has experienced this and what your solution was.