Need Help with PEX/Shark bite pipe fittings

Inspected an older home today here in Phx, home had been repiped with PEX piping, pipe has the name Sharkbite stamped on it, but also says PEX in fine print. My problem: The brass fittings, which have little sharks molded on them were leaking throughout attic. I googled this and did not find any recalls on these particular fittings. does anybody know if there have been issues with them, obviously this house has issues with them. I am having trouble adding photo, sorry.

Look for the mark that the installer is supposed to make one inch from the end of the pipe. The mark is the only way to know when you have pushed the pipe far enough into the fitting. You should see the mark very near the fitting. The technology is old enough so its probably an installer error.