802.11r enabled on both bands per AP doesnt work

[Deviance]

802.11r on one band (2,4GHz or 5GHz) per AP works with:
mobility_domain=e612
nas_identifier=<unique per BSS>
ft_psk_generate_local=1
wpa_key_mgmt=WPA-PSK FT-PSK

While using those parameters for both bands per AP, client wont roam
to higher/lower frequency on the same AP, neither to the other AP. It
looks like the client is stuck.

Am I misunderstanding the whole concept here: FT can only be used for
clients to roam between APs and not bands on the same AP or are the
parameters incorrect for this setup (both bands per AP)?

hostapd v2.7-devel
latest LEDE trunk
Archer C7 v2 (all APs)