Here is my theory....
The target trigger, hammer, sear, etc are all set to very close tolerances. They need to be in order to get the nice crisp, low weight trigger pull that is decidedly lacking in a factory 10/22. However, to get that crisp trigger pull, the bearing surfaces are much smaller. I suspect that in the rather fast and violent movement of the bolt flying back, the hammer is not catching on the sear and rather that staying in the "cocked" position like it is supposed to it is riding the bolt as it closes and ends up in the fired position once the cycle is completed. When you pull the bolt back part way it is much more gentle and this allows the hammer to "catch" this time and remain "cocked" until the trigger is pulled.
I bet when you return the factory parts it will function just fine, but have the atrocious trigger pull.
If your sear/trigger/hammer is adjustable (as it seems you have) when using it for the first time, have it adjusted so that the trigger is still heavy and gritty. Then run it like that for a few hundred rounds. That will give the mating surfaces a chance to "break in" and mate better, once they are a broken in, then try to adjust for a lighter trigger pull.
I have not used an adjustable trigger/sear on a 10/22 but I have used Rifle Basix triggers on a Savage and a Marlin and found that when it was newly installed I could not get the really light trigger pull I hoped for while retaining safe, reliable performance. However after a while with the trigger set "heavy" the mating surfaces wore enough that I was able to safely adjust the trigger down to a very crisp 1-1/2 lb or so.
Good luck