A word or phrase for "The problem solved itself"

The appliance repairman who tried to repair the interlock on my dishwasher could not replicate the fault. He made no repair, and the dishwasher worked fine thereafter. He marked the ticket, "FM." He said this was standard US Air Force lingo for such a situation, with the 'F" standing for same as in SNAFU, and M standing for "Magic." In my opinion, if it's good enough for the men and women who keep our jets in the air, it's good enough for me.

The self-explanatory term self-correcting may do

Correcting oneself or itself without external help

If you seek to emphasize your utter lack of understanding of the mechanism which brings about the consummation devoutly to be wished, you could say

inexplicably self-correcting

Not quite the same situation, but when an issue has been rendered irrelevant by other factors, we close the ticket as OBE - Overtaken By Events.