I have an I-Pass, and in 2017 I took a lengthy road trip that involved travel on the Illinois Tollway (limited, I think, to the I-80/I-294 barrier toll at Hazel Crest), the New York Thruway, and the Ohio Turnpike. My Tollway account auto-replenished at least once (I have set a $10 threshold and $10 top-up each time) and, AFAIK, never once went into the red.
I will say, however, that I have seen yellow at the blue/yellow lights on the Tollway at times when my account was nowhere near the auto-replenish threshold. This has never resulted in a video toll, however. I suspect the equipment is highly reliable but not 100% glitch-free.