Guest network firewall logs

HI,

We have a number of APs managed through Sophos Central. We have a specific guest SSID which is using NAT and a captive portal, but still going out our on premise sophos firewalls.

I can't seem to get traffic through this SSID to log in the firewall though. I get 'could not associate packet to any connection' drops (which we see a lot of anyway) but that is it. Clients are working fine on this SSID. Other wifi SSID clients are showing traffic logs as normal on the firewall.

Any ideas?