It's probably an ignition relay going bad but since this is the US transit forum there won't be a ton of help for your 2012.
If the engine keeps running it may be in the accessory relay which powers the electrical stuff asid the from engine controls. Just pull them and replace them or tap on them one by one when the issue occurs and see if one will respond and re-connect the power while tapping.
If the engine keeps running it may be in the accessory relay which powers the electrical stuff asid the from engine controls. Just pull them and replace them or tap on them one by one when the issue occurs and see if one will respond and re-connect the power while tapping.