Sextant and altar rewards not dropping from final map boss

In City Square, all league when i'd choose a reward like map boss drops an additional map from the altars, nothing would drop.

I've now noticed since socketing a sextant that says 'final area boss drops an additional conqueror map', again nothing drops. it only seems to be with map rewards, but it's annoying af and stealing rewards from the player.

Turns out after a bit of digging that Singular Focus completely stops conqueror and elder guardian maps from dropping from altar and sextant rewards despite being able to drop naturally while the node is allocated.