I finally found the cause of my signal loss after 6 hours of chasing
Went back to a house in Columbus where I'd already rerun the drop twice, still getting intermittent failures. Turns out the ground block was installed upside down from a previous job and water was pooling in the connector every time it rained. Anyone else ever get burned by something that basic on a return trip?
Honestly I always thought it was the cable itself or the connectors that got you on a return trip. But yeah the ground block being flipped is such a dumb simple thing and it will absolutely ruin your day. That's the kind of thing that makes you question every basic install you've ever done.