I think you may have found a genuine problem. Spectra is pretty abrasive. If there really is a problem, you should contact HH. They would have a real product liability problem and should either recall the straps or put out an advisory notice. Someone could badly hurt their back if this fails while hanging over rocks or a gully.
Please let us know how you tension your lines. Do you pull the spectra line through to full tension, then bend it round and tie off, or do you pull against the tree drawing it through the loop like a "commando wire saw" drawing against a sapling?
For what it's worth, if you get a new set of straps, a stainless steel triangular quick link would eliminate your problem.