I actually have been having almost the same issue! After 9 months + of perfect charging with my Mobile Connector and 15-40 outlet, my car would not charge. Charger lit up like it was charging (flowing green lights) and the charge port showed flashing green (until sometimes it would turn red after about 30 mins). The screen showed that it was charging and would give an eta to completion. Showed the voltage (235-249) and amps at 0-2 with no miles added per hour. I took the car to Tesla and they said there were no issues they could find. The car charged fine at Supercharger and on chargepoint stations. Tesla replaced my mobile wall connector and I had no issues at home charging. Then, 3 weeks later, same problem. Like you, my mobile wall connector worked fine on the 110 plug at home. Also, the loaner model s charged on the 15-40 plug at my home with no issues. The service center says there's no problems with the care and sent me on my way. I have been intermittently able to charge at home with my MWC and 15-40 plug. I put a call into Tesla Customer Support and they have escalated the issue and I'm waiting to hear back.
Also, I have had the electricians back out to verify all components as well as had the electric utility do line voltage verification...all of which came back perfect.