The watch doesn't know if it's AM or PM, so if it's stopping at a particular time then it's the positions of the hands on the dial that are important and not related to it being AM or PM. However it can be related to how recently the watch has been wound, which affects the torque being delivered from the mainspring.
So in the time frame you mention, the hour hand is over the sub-dial where the constant seconds hand is located at 9 o'clock, so it could be that the hour hand is touching the seconds hand, and when the watch is fully wound in the morning it has enough power to pass by the seconds hand, but by the evening the power has dropped off enough to stop it. You could try winding the watch at 7 PM, and see if it stops or not - that may give you a clue.
You could try to visually confirm if the hands are touching, but it might be difficult to see well enough through the crystal - better confirmed with the watch movement out of the case. Really need a watchmaker to look at this and diagnose what's going on, but not sure what implications doing so would have on whatever warranty Jomashop offers.
I've never dealt with Jomashop myself, but based on all the interactions I've read about, their warranty service is lacking. Not sure what options you have but maybe getting them to have someone local to you fix the problem would be better than sending it back, but I doubt they would agree to that.
In the end this is one of the risks you have to accept using grey market dealers.
Cheers, Al
Click to expand...