@MrGermaine23, sorry for all the questions, but this sounds like an odd issue

What kind of meter are you using, and how do you calibrate/store it?
And did all your beans come from the same shop, same shipment?
Good call trying a test with different soil, but even with a total crap medium I would expect more growth before a lockout, and when I mixed an overly hot soil it was painfully obvious

It seems likely that either your pH is insanely out of wack, or perhaps the seeds went through some ordeal that hurt their viability (age, extreme temperature swings, etc).
A careful look at your soil and stem base - especially after watering - would also be a good idea, although I think something like root aphids would cause noticeable damage that I don't see in your pics.
I've never had an issue with my humidifier. I use well water (fairly hard). Every 2 weeks it gets a good scrubbing with water and apple cider vinegar, and I run a tank through it with one part acv, two parts water.