EGT thermocouples are also notoriously fickle as well - something to keep in mind when you can’t figure things out.
You can stick it in boiling water for a quick check (100ºC/212ºF) if you’re around sea level.
A low EGT can also mean unburnt fuel/oil; but it would need to be quite bad for that to happen; though an intermittent misfire can lead to that.
There’s some good back-and-forth on the merits and pitfalls of EGT tuning/monitoring here: ROK Shifter EGT's