Unless it is extremely cold the cells should do ok , such as indoors or what have you. Maybe try the routine stuff first like cleaning the contact points (springs , tube ends and any other point that makes the contact). Also make sure the retaining rings are good and snug as they many times get slightly loose.
Yes have tried all the above.Have same problem with my TC20, used a Mollicel 20700 3000mAh in an adapter that did the trick.
Hmmm don’t know what might cause that problem to be honest.
Same here stumped.
Even tried warming the light.
My Rofis MR70 is the same, no matter what cell I use.
Well it sounds like one of those mysteries that needs solving , but no idea where to begin.