Rear wheel landed on a rock hard a few months ago. Sealant didn’t fill the hole so I used an inner tube to continue the ride… and it stayed in there for a few months. Got some of those repair mushroom plug things (3mm) that were mentioned on a thread here somewhere.
After removing and cleaning mud off tyre couldn’t find hole. Put it back on rim without tube to hopefully hear the air escaping to identify hole. No air escapes, but hole is visible, a ~5mm slit. Tyre in question is Specialized Purgatory Grid 27.5×2.35. It’s been pumped up for an hour now with track pump still attached.