The existing probe with a couple of holes has been working, one LED was punched out with a third hole that tactically went straight through it. It’s still there, just below the surface.
Did you check that the LEDs indicate it’s working and lights up before probing? Dead batteries are common.
The new one has been around for awhile. Although a newer build from the same mfg, the aluminum plunger switch was too tight in the sleeve of the molded plastic body, it wanted to bind and read as touched. It’s glued together so we can’t take it apart to sand the sleeve interior. I did try a bunch of stuff including heating the aluminum and working it back and forth. Got better but was still pretty bind-y but it could have gotten better with time.
The transmitter and receiver are hardcoded to only talk with their corresponding device. So using the other probe does mean the receiver must be swapped out too.