RoutTableId get not tranferred into a !Ref <value>

[ustrahlendorf]

Describe the bug
I see the following in the output for CFN:
ec2a5a8cd6:
Type: "AWS::EC2::RouteTable"
Properties:
VpcId: !Ref ec20062a21

ec29da2ac9:
    Type: "AWS::EC2::Route"
    Properties:
        RouteTableId: "rtb-0e63402f072e08d8e"
        DestinationCidrBlock: "0.0.0.0/0"
        NatGatewayId: !Ref ec2369c7ba

ec21c10d70:
    Type: "AWS::EC2::SubnetRouteTableAssociation"
    Properties:
        SubnetId: !Ref ec2b18debb
        RouteTableId: "rtb-0e63402f072e08d8e"

Going through the whole template it is just the RouteTableId what did not get transferred into a !Ref.