I wouldn’t necessarily give up on that other than frustration. The bluelabs are usually one of the better consumer grade probes. PH probes can be tricky if they act weird, require some regular attention, and, particularly, you don’t know how they were handled by the reseller or how long it was sitting around.
I have the bluelab pen for, idk, maybe three years or so. Still works like a champ. But I’ve also had much more expensive scientific grade probes act wacky and it was mostly due to air bubbles in the bulb or all of the ions leach out (why you don’t store them in distilled water). Was recoverable though. Never let them ever dry out though.