Recently ordered a new kit and the aluminum tube inserts snap almost immediately, leaving the nyloc nut spinning uselessly inside the tube. It's then almost impossible to get it off the screw, so I now have the tubes barely attached to the base dibond sheet and no way to remove them or tighten them. Any ideas?

Fixed it, had to jam a screw into the tube to push against the nut and produce enough friction to keep the nut stationary. Two of the inserts snapped, so I wrapped the last two in a layer of tape to bridge the small space between the plastic insert and the aluminum tube, which worked. Maybe these should be slightly redesigned so they can be printed in a different orientation?

I did the exact same thing. It happened to only one of them in my case.

I found it easier to just tap the alumnium tube and not worry about the nuts.