John, Was the ground fault trip setting ever set after the main was installed? They often come from the factory set at the lowest setting and it is not uncommon to have the main trip on ground fault without tripping the branch breaker when the main is left at the factory setting.
The main was tested and 'set' by a factory tech from Siemens after initial install & energization. Factory tech returned after this incident & checked; all was within previously set range.
