I can't believe people still act surprised that frame locks are susceptible to this. It's 2019 people!

The list is loooong and well documented across production manufacturers, mid-techs, and customs.
As a lefty I've never been into frame locks anyway, but I never got their wild popularity or reputation as a "hard use" lock. For the most part, it seems like locks that fail even weak spine whack tests aren't much of an issue for people in everyday use though. Maybe that's why their dominance persists? I.e., the massive ZT threads where people were shocked, SHOCKED, and then ultimately didn't care lol.
Not trying to defend the Paysan in particular or say it shouldn't have better QC/tolerances/whatever, but at this point I'm not sure why people expect what they do from frame locks anymore.
Even perfect out-of-the-box specimins will wear over time. Lock stick... unacceptable. Steel inserts may actually make them even more prone to shifting/whack-failure. Late lockup is unacceptable. It developed up and down play. Etc...
GLTA