Just checking in to say I'd never had this problem after 35 months of leasing the 2013 C-Max Energi, but it just occurred. Pulled Fuse 67 and reinserted. Almost instantly got a text message confirming the last command I'd sent with the app (a week ago)! Funny it stays in some queue that long.
Fuse 67 is in the fusebox beneath the passenger side glove box (pull the two caps off the yellow studs, then pull the carpeted cover down and away. Fuse 67 is the red 7.5 amp fuse that is the 3rd fuse down in the second column from the left. It's got a blank holder beneath, so it's easy to spot. You'll need a fuse puller or a pair of strong tweezers to get it out, but it goes back in very easily.