Routes to ENI in VPC rt do not propagate to attached TGW rt

Question

I have a VPC attached to a TGW in same account. I've added a couple of entries to the VPCs route table with an ENI (or instance) as target.
I expected those new routes to propagate to attached TGW's route table automatically but they don't.

Should the routes in VPC's RT propagate automatically o do I need to add appropriate entries in TGW's RT targeting the TGW-VPC attachment? What could I be doing wrong?

Accepted Answer

TGW route tables and VCP route tables are two separate route tables and you won't be able to propagate the VPC route table into the TGW route table, when you propagate a VPC attachment then you ONLY propagating the VPC CIDR into the TGW route table.
Use static routes to add a specific route into TGW route table.

Routes to ENI in VPC rt do not propagate to attached TGW rt

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