Contax RX shutter - The first press of it will not actuate the shutter or the mirror, but fine afterwards.

This happens occasionally when the camera was rested/not used.

Any thoughts what would cause this?
Just picked up the camera recently on eBay, nothing wrong with it except that each roll I shot will have 2,3 blank shots because of the issue.

I had the same problem with my rx. Fixed once, the problem recurred a year later. In short, I gave it away as spare parts