Its better to have fact than to guess so I would suggest You would have to send me a few dozen for me to inspect and run test on in order to see what the problem is. I could send you a report on the testing free of charge lmaoooooo.
If I had to guess I would go with humidity as Jacq
stated, that is if you have good quality stogies. Now if you are smoking Dog Turds them things you light the foot and the other end starts burning. I was keeping my humidity in the 70 to 72 range and was having those issues. I cut back to 67 to 68 now razor sharp burns. I was amazed at what 3 to 4 % could make.