Loose breaker on inverter #2.
Loose wires going in to inverter #2.
Loose ground wire connected to inverter #2.
Seems like this is the place to start looking, around inverter #2 breaker. After you remove it, smell it. Does it smell like what you described in your OP?
Breakers are easily replaced. Turn power main off, loosen screw holding wire on breaker, lift breaker off electrical panel, snap new breaker in its place, re-install wire you just removed, turn power main on, turn breaker on. Good luck.
Lakeside