Bottom timer said 12 minutes but I was down way longer, trust your gut
Working a salvage job off Port Angeles last spring, my bottom timer froze at 12 minutes while I was clearing net off a prop. I knew from the currents and my air I was pushing 20 plus, so I thumbed it and came up slow with a 5 minute hang. My tender thought I was being a baby, but my deco schedule showed I was right on the edge. Trusting the math over the gauge is what kept me out of the box. Anyone else had a dodgy instrument and just knew to bail early?
Had the same thing happen on a dive off Monterey, my computer locked up at 40 feet and just sat there while I was working a stuck anchor line. I could feel the pressure building in my ears and knew from my bubbles I was way deeper than it showed, so I started my ascent on my own schedule. Took a long safety stop at 15 feet and still felt off for a couple hours after. That gut feeling is real and it's saved my butt more than once.