We have a setup with 2 Boxes with one provider on each box:
PFsense 1 has Provider A (1 LAN Interface which is using also the PFSync, 1 WAN Interface)
PFSense 2 has Provider B

Over this we have IPSec VTI with BGP Setup.
This works fine when Provider A fails. All the VPN Networks are still availabe over PFSense2.
But the Internet is not working anymore, because the CARP-GW is still on the PFSense 1 which has no Internet access anymore.

So therefore I set up a Gaweay-Group on PFsense 1 -> If Provider A is offline use PFSense2 LAN IP as Gateway.
Now If I test now the failover with a ping test. one ping is successfull but every next is gone.
Traceroute is always working over that path but with ping only the first packet.

any idea what's the problem. Is the NAT State Sync maybe a problem?

Other nice solution of that problem would be if there is a possibility to change the CARP-GW if the WAN fails.