As the others have pointed out: Maya Prime is seemingly referring to
two different things.
Sensei has been hallucinating since at least the Accident, if not since he was born considering his mental issues seem hereditary. He's also been blacking out since presumably the Accident, and Ami likely has as well.
His Hallucinations and Blackouts are seemingly Pre Reset things, and things that he's had since the tutoring days. Maya is well aware of them since she had been dealing with them for around 8 years, even before the Resets.
However, since the Resets, Sensei seems to go into shock, delirium, and/or die from hearing about/remembering his and Maya's relationship, or even hearing her say she loves him (Presumably, Sensei's feelings for Maya are literally dangerous). Apparently, hearing her say she loves him has more or less killed him quite a bit:
These Maya related Episodes seem to be what Maya was referring to as something Sensei has had since the first Reset/loop.
It doesn't seem like she realized how related to them she actually was, and that's likely why she didn't understand how the Nakayamas can do things that would be fatal to Sensei, if she did them instead:
They also don't seem to matter much when it comes to New Maya, albeit it could be due to other factors at the moment.