unable to screw in crown 3120

[timeskeeping]

Hi All, i'm new here and have been searching around the forum however i cannot find the answer i'm after.

I have a 15300RO with 3120 movement, I have the watch in manual winding position on the crown however when trying to wind, i feel a very strong resistance, not allowing me to wind. I've left it for 18 hours without wearing it and have come back to it to find that i still cannot wind the watch.

Is it because the power reserve is full, is something in place preventing it from winding?

I can change the time and date without any issues and watch is still running as we speak however as this has occurred, I cannot screw in my crown.

Has anyone else had this issue?