IPv6 with CAP AC in repeater mode not working

Hello together,

i have a problem with my CAP AC which act as a wireless repeater. The clients which are connected to it cannot reach anything over IPv6. They are getting correct Addresses but cannot reach anything with it. Nothing in LAN and WAN.
If i connect the devices to the AP (also CAP AC) where the Repeater is connected directly to, everything is working fine.

Does anyone have a idea what is going on here, because the repeater is only configured as a bridge?

The firmware of all devices is 6.44

Thanks for reading this!