Frozone does know his stuff.
A tc works by the principle that dissimilar metals connected to each other at a small point generate a very small voltage at that point (bead), and the voltage, expressed in millionths of a volt, is temperature dependent. Introducing connections made with a different type of metal along the way to the final destination (PID terminals) will likewise create voltages that conflict with what the tc bead generates. There's your banana plugs.
I had a similar experience-
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