Means that the lightning payment did not pass and failed neither (IN_FLIGHT status on LND). Depending on failure type can take from minutes to days (very rare) to resolve, mint can't do anything about it.
In some cases, mint might not get update about the resolution of such payment so if there is such case, dm me the payment hash.
On wallet side, ecash passed to settle the payment needs to stay out of spendable balance until it resolves (move back to spendable if it fails)
