Client Authentication Agent only logs in with IPv4

I've installed Sophos XG Firewall Home Edition to protect my home network. I am using IPv4 and IPv6, since I have some devices requiring IPv6 to be active.

I've setup some firewall rules so only authenticated users are allowed to access the internet.
FYI: It's a pity firewall rules have to set up on IPv4 as well on IPv6 (same for host definitions etc.). Maybe this can be a future improvement (it was handled beter in UTM).

I am using Client Authentication Agent on my desktop and notebooks to authenticate the users. Looking at "Live Users" in "Current Activities" I only see users authenticated on IPv4. When trying to access internet on a desktop or notebook I am redirected to the captive portal on which the XG states I am not logged in.
FYI: I am redirected to IPv6 address of XG, where I have to deal with certificate error. I suppose the IPv6 address is not included in the certificate generated on the XG? Some future improvement as well...

It is possible to log in via "web client", this is also shown at "Live Users" in Current Activities" (this time with IPv6 address). However, in my opinion, when using Client Authentication Agent it should take care of both IPv4 and IPv6 so this does not happen.

Anything I can do about it?

I am using Sophos XG Firewall with firmware SFOS 16.05.3 MR-3 and Client Authentication Agent v1.2.1.

Thanks in advance!