I have 2 Axis rifles, one of which I’ve had since the month after they were introduced. I’ve never experienced similar issues to yours and I have several thousand rounds through these 2 rifles. Both have aftermarket triggers.
Here’s my list of things for you to try:
First off, give me the honest truth here. How many times have you cleaned and lubricated the rifle and the bolt specifically?
My #1 suspect is either the bolt, spring, firing pin is dirty, OR the more likely is that you applied too much oil, grease, or other lube and some of it is turning to gel in cold weather and slowing your firing pin travel. This is common with all types of rifles. And it doesn’t take much! I once went CRAZY with a Contender pistol that had this exact issue, it went bang 300+ times in a row in the summer, in the hunting season it went click on the first try.
You say you took the bolt apart but did you clean the spring and internals of the bolt?
Shooters are always worried about not using enough lube, but in truth the most common issue is too MUCH lube. When I did the IDO review on the Axis rifles when they first came out, I noted specifically that the first thing I had to do is strip the gun and remove the 12.7 ounces of grease, oil, and preserative goo that the factory applied. IIRC, the bolt had grease applied. Which is sure to produce a failure anywhere north of Alabama.
If you did not already do so, I would strip and clean the bolt again. Degrease it completely including inside the bolt itself. Then apply a spray rust preventative lube and wipe it clean so only the metal surfaces are shiny, there should be no drops or excess liquid lube anywhere. You are only putting preservative on as a rust-preventer, this area does not need lube and certainly NOT grease. Make sure the bolt face and firing pin hole are clean and clear of debris.
Strip the bolt all the way including using the Allen screw to remove the bolt head itself, so you can clean inside the bolt face on the inside of the passage where the firing pin passes through to the bolt face. Degrease all these parts. Leave no oil or grease.
Also, look up a diagram and make absolutely sure you have reassembled all parts in the correct sequence. From the firing pin, there is a spring and a washer. Make sure those parts are present and in the right order.
Additional question: Have you replaced the stock? If yes, there is another Axis specific issue you need to check, but I won’t detail it here unless you say you’ve replaced.
Even though you are using an aftermarket trigger, that is not my #1 suspect IF it is installed correctly. I strongly suspect an over-lubed/greased bolt is the issue here.
Grouse