A ground-fault circuit interrupter (GFCI) uses a current transformer (CT) (or similar device), to detect slight current imbalances between the ungrounded (hot) and grounded (neutral) conductors that pass through it. On its own, a GFCI does not offer any purposeful type of overcurrent, nor overload protection.

What does GFCI protect against?

The GFCI is rated to trip quickly enough to prevent an electrical incident. ... However, it protects against the most common form of electrical shock hazard, the ground-fault. It also protects against fires, overheating, and destruction of wire insulation.

What happens if you overload a GFCI?

Overloads don't trip a GFCI.

If there was an overload, it would trip the actual circuit breaker. Since this is a GFCI/receptacle (as opposed to a GFCI/breaker) and the GFCI trips, that is a GFCI problem - 100% - and not an overcurrent situation.