Yes in reference to this, "Your description of a separate meter for EVSE implies that the 240V circuit for the EVSE needs to have its neutral wire bonded (connected) to an earth or plumbing ground at the meter. Your Juicebox would then be connected behind a new 50A breaker."
The electrician created a ground at the meter, and there was a new 50A breaker.
But I will reference all these ideas when I contact the electrician.
I hope this doesn't become an intractable problem for me.
It should not be a problem, yet you should have your electrician check it out. There are still other possibilities including the Juicebox being defective.
Taking the hypothesis that your electrician made an honest mistake and wired the EVSE disconnect as a sub-panel
(a panel connected to another panel through a breaker), the electrician would not have bonded
the neutral to ground. This causes a problem for the EVSE.
Here is a diagram from an electrical inspection
A subpanel (on the right) has no connection (bond) between a local ground and the neutral.
When Juicebox asks installers to "not use the neutral" and connect only the ground of a 4-wire circuit, Juicebox designers are assuming their EVSE will be connected directly to a breaker in a main panel (middle). In a main panel, ground is directly connected to neutral.
The problem is that all of the electricity coming into your Juicebox is referenced to the neutral line, and really
wants to get back to neutral. If you connect a Juicebox to the right hand side sub-panel, you throw a very long circuit for ground to get back to neutral. This may mix up ground faults or affect any 110V used in the EVSE (for 12V DC, for example).
Again, your electrician probably did the correct connection, but if not, correcting it is just a few screw turns. It's worth a check.