I had a similar experience. I worked in a neuroimaging lab during grad school. I found a mistake in our code that basically meant we had being overestimating the p-value from MRI data. It potentially invalidated many of the previous papers (and there were a lot, this was a "paper mill").

Being naive, I just assumed they'd be retracting them, but my labmates explained there was no way our PI would let that happen. It was never boiled up to the PI, so he never even knew. A year later (due to this as well as other issues), I quit the PhD and joined a company doing something "real".