If the carto tests well for resistance on a multimeter, then it is likely that something happened to it while it was screwed in...maybe the centerpost got pushed up just enough to have this tenuous connection. I have found something similar with my Boge LRs on one of my KGO batts. Not the same, but similar. It will not charge with a 510 extension in a regular 510 charger. Charges fine on the KGO charger. Also, if I put a fresh carto on it, it vapes great. Go
through one charge cycle with that carto, charge the batt, and now that perfectly fine carto, which is working on other batts, does not work on this batt. Put a fresh one on, and its fine. Put a carto on that was being used on another batt, and its fine.
My point is not all batts are identical in terms of their connectors, and it seems some models tend to crunch on carto terminals. Make sure all connections are clean (I use a paper towel rolled up to stick in the batt connector and twist it around). This can help, as often a black char material forms between the batt and carto/atty. If a fresh carto works fine, and one you had been using a lot is not, then the above described could well be happening to you too. What might help in the future is to not screw the carto in too tightly. Just enough to make contact. With some cartos, you can take a safety pin and stick it into a side air hole and pry downward, and the center post will slide down about 0.5 mm. Just tried this with my Boge LR carto that would not work on the "bad" KGO batt, and now it is working great. So it seems there might be something to this. If I screw it in tight it still works, until I take it off and put it right back on. Then it doesn't until I slide the center post again.
Perhaps this will help you. Although the problem is not exactly like yours, my point is that some batts will change the terminal on the carto enough to keep it from working if taken off and put right back on. If the batts are still new, you might be able to get them replaced, but since this is likely manufacturing of the batt itself, this might not solve the problem.