I don't know how to tell if this is GCCM map - I can't find any listing of the GCCM map images to search for.

Link to screenshot of the map https://imgur.com/a/aBQ3t55

It spawned on me during a battle at sea, just to South East of the province of The Galleon's Graveyard.

I am playing as Bretonnia attacking Dreadfleet army that just swam out of the Galleon's Graveyard. I suspect GCCM as it's not a normal island battle map and it seems out of position for the ME campaign map .

The map has horrible pathing issues which as the screen shot is displaying is currently costing me the battle. The giant rock formation in the middle, which looks as perfect cover for splitting enemy advance and for my archers to shoot through is producing constant glitches - through out the battle my ranged units suddenly rush into melee to attack enemy units around the rock formation despite having clear lines of fire for both direct and overhead. One of my trebuchets which started far behind the rock (see the 3 top yellow dots on the map) was tasked in beginning of battle to fire at an enemy unit - I didn't think it mattered that the line of fire would go over the rock until I noticed that said trebuchet crawled out of position and trying to drag itself around the rock. It looked to have clear line of fire to its target.

Pretty much the only thing interesting about this map is this giant rock in the middle and it's seriously buggy.