ipv6 subnetting "this ipv6 address exists in the subnet of the outside interface" any idea how to proceed? - enterprise serverrack

Configuring the asa 5506-x through the ASDM, trying to attach a /64 to my "inside" interface.

My config is as follows (example ip's):

outside interface: 3002:6c2:9405::/48 Gateway: 3002:6c2:9405::1

Static route from any6 to 3002:6c2:9405::1 and i can ping ipv6.google.com from the asa itself.

When trying to add the following subnet to my inside interface: 3002:6c2:9405:1103::/64 i get the error "this ipv6 address exists in the subnet of the outside interface"

I tried a lot of different combinations, i even tried to attatch a /52 to my outside interface instead, but then i cant ping anything ipv6 from the asa.

I'm kinda stuck here and i'm convinced i just overlooked something easy, could you guys push me in the right direction?