Disappearing convoys

[Gar-Dog]

The last thing the Brits want in this game is to lose convoys to interdimensional portals...

When I open the Naval movement interface, go to the Liverpool navy, and right-click / "Merge" convoys (a 10, 3, 3, 1, 1) it makes an 18-size block that's selected in-hand. I wanted to move it with other ships, so I hit ESC. Instead of putting the 18-stack into Liverpool, it disappears from the game as far as I can tell. It's neither in the SZ I was hovering over (Faeroes Gap) nor in Liverpool or Bay of Biscay.

I'm guessing there's a workaround, but this at the end of a very long British naval move with lots of interceptions made for a difficult lost time...

Savegame attached / ready for eval.