SDN: IPAM NetBox: "create sdn subnet object failed: error add subnet ip to ipam: ip 10.0.0.1 already exist"

[MathieuMD]

While trying to add a subnet to a VNet, PVE fails because the subnet's gateway is already existing in NetBox. The error popup says:

create sdn subnet object failed: error add subnet ip to ipam: ip 10.0.0.1 already exist: at /usr/share/perl5/PVE/Network/SDN/Ipams/NetboxPlugin.pm line 109. (500)

I could create subnets whose gateway was not yet existing in NetBox, though.
Is it normal behavior? I guess it should silently ignore already existing IPs.