Bitdefender firewall blocking SSTP VPN (RRAS) — any fixes?

I’ve got a Windows Server running RRAS for SSTP VPN.
When Bitdefender firewall is enabled, the VPN connects but no traffic passes through.
If I disable the firewall, everything works fine.

It looks like Bitdefender is blocking the RAS adapter traffic — has anyone actually found a way to make this work, or is the only option to disable the firewall module on the VPN server?