5th Map Device Slot cannot be unlocked

I am trying to unlock my 5th map device slot by doing a Maven's Invitation: The Atlas in Standard SSF. For some reason completing the invitation does not unlock the 5th Map Device Slot.

https://www.poewiki.net/wiki/Map_Device#Mechanics

I am also having this issue and am struggling to find information is this is due to a bug or because the 6th slot is exclusive to league?

But I am in SSF Standard and Maiden is not unlocking an additional slot for me. Don't want to brave a T17 yet, don't know if doing that will fix the bug, but either way Maiden 10 way (completed about 5 or 6 of them) is not providing an additional map slot.

This was resolved upon completing a T17 where I got both added map slots. SSF: Standard, character made before the 6th map slot was added but with a prior Maven 10-way kill.