Confirmed. This is an old bug that appears when you have enabled parental control;
Without parental control:
-A FORWARD -d 192.168.100.1 -i br0 -o eth0 -p tcp -j DROP
-A FORWARD -i br0 -o eth0 -j ACCEPT
-A PControls -j ACCEPT
With parental control:
-A FORWARD -i br0 -m mac --mac-source 34:14:5F:3E:C7:8B -j DROP
-A PControls -i eth0 -m state --state INVALID -j DROP
-A PControls -d 192.168.100.1 -i br0 -o eth0 -p tcp -j DROP
-A PControls -i br0 -o eth0 -j ACCEPT
-A PControls -j ACCEPT
So it seems that enabling parental control moves the NSF rules into the PControls chain, whilst putting the parental control rule into the FORWARD chain.
I'm not sure how the PControls chain is intended to be used as it isn't called from anywhere.
EDIT: To see this bug parental control must be enabled AND have at least one rule setup.
Ah, did not turn on parental control as of yet, so a factory reset didn't resolve it. Thanks for the heads up.