It's a long shot, but look for intermediate air leaks. Sometimes I'll have a cigar that draws well, looks like it's lit well, but for some reason, good healthy draws yield very little smoke and the cigar just goes out. And overall the cigar just feels off. I've found the culprit is often a very small air leak somewhere in the middle. Not so much that smokes comes out of it and you notice it, but enough to drop the pressure of your draws under the threshold for keeping the foot lit. Very weird, but the next time it happens, check carefully for air leaks and maybe you can find one that's easily fixed and then all is right with the world.