I own an Argus Cosina STL1000 with the same shutter and in very cold weather - like -30 C when I used it for the first shot after having it at room temperature it would not fire the shutter - got the mirror flap etc. but always a blank shot. I put it in the freezer - in a plastic bag to keep dry - with no film and the back unlatched. Let it get cold and then watched when I fired it. Every time it went from warm to cold the first shot was lost due to the shutter not working. Pure mechanical shutter. So my cure at the time was to always take the first shot twice if it was something that mattered.
A quick check using the freezer should indicate if this is also the problem. Once the first shot was done all the rest worked until the camera was once again warmed up and taken back out in the cold.
I don't take photos in that kind of cold as I moved a lot farther south and in winter most often shoot with a Pentax Spotmatic that doesn't have the same issue.