If I were to guess, and this is not from lots of product knowledge, my guess is that during the manufacturing process, whatever happened, the crosslinking process was not performed completely or properly. The crosslinking is what creates the memory. If it's not to spec, they would not be as strong, nor would they collapse as tight to create the seal with the fitting...it the worst case, the links would break, and a crack would form.
One of the main differences between the three types is the amount an method of creating the crosslinking in the tubing. Type-A has the most crosslinking, and as a result, is the only one that can work with the expansion tool. The others don't have as much flexibility, or as much memory. Seems that the tubing is acting like a type -B or -C, not as type -A that it should be.