ECS fargate container cannot connect to Amazon Managed Blockchain Peer endpoint

We have VPC endpoint setup. I have simplified the connection problem down to a netcat command

when ran directly from an ECS container shell it hangs then times out

$ nc -v nd-wdas<removed>.managedblockchain.us-east-1.amazonaws.com 30003
nc: (10.0.0.77:30003): Operation timed out

from an ec2 ssh console the same netcat command returns:

$ nc -v nd-wdas<removed>.managedblockchain.us-east-1.amazonaws.com 30003
Ncat: Version 7.93 ( https://nmap.org/ncat )
Ncat: Connected to 10.0.0.77:30003.

The ECS security group for the container is the same SG that the working EC2 uses which allows all outbound connectivity. As a side note, we dont have any issues connecting to EC2 services from ECS (everything is all in the same VPC, same subnets)

This problem seems to relate to routing ECS traffic over the VPC endpoint to Amazon Managed Blockchain. Any ideas?