It is not clear to me if anyone has tested this on a properly grounded 208 outlet but if they have and it does not work then Panasonic has set a a hard voltage limit with the assumption that 208 could be a voltage issue as residential 14-50 outlets should be 240V, Pretty simple and there is no conspiracy or mystery here. This tread is 5 pages long and all questions presented were pretty much answered:
Design of the unit dictates a properly installed and inspected 240V, 50A circuit, anyone that does that won't have an issue. End of story, not sure how much easier it can be. It's not:
Designed to be used on 208, with other outlet types, etc.
There are no conspiracies, etc other than for those that do not use it as intended. Anyone that has a properly grounded (properly verified) 14-50 circuit having issues yet?
Those that do not want to use the EVSE as above should buy another product or they can continue complaining and speculating about all the reasons it won't work as designed on the other 5 plus pages this tread should have by year end.