Sounds like an odd problem. I wouldn't take it to the dealer until it is 100% reproduceable. Your experiments are good, just be sure to write them all down and it will help you see the pattern if there is one.
One thing you can try when it does this, and provided that your link with myfordmobile is working...after plugging it in and seeing that it doesn't charge, go to myfordmobile and see what the status is. It will say something like "MY EV is at home, plugged in waiting to charge" or "MY EV is at home, unplugged". Be sure to do an "update" to get the current status. This could tell you if the car knows it is plugged in; then it might be just an issue with "value charge" and could tell you what it is waiting for.
Also, when you plug it in, does the blue ring around the socket light up? If it doesn't, try removing the plug and re-inserting. I've had this happen to me where it just didn't quite seat correctly and it didn't charge. I do know that it does get confused sometimes. With value charge, I plug it in, the blue ring lights up and then no charge. The lights remain static and eventually go out and wait. I have had it charge regardless of value charge because I was below 10% charge, so it charged up a little and then waited for the value time. However, the other day, after I plugged in, it started charging...although I didn't check the meter to be sure. The blue ring quadrant was pulsing. I popped back in the car and checked the charging time; it was set to charge at 12:00am. My battery was at 57% so I couldn't figure out why it seemed to be charging. So I unplugged and then re plugged and it went back to normal.
Anyway, I haven't had any issues like yours, but I think if you check the myfordmobile site to see what the car sees, at least that might narrow down the problem...and make sure the blue ring flashes when you plug it in.