elb ssl termination for wss websocket fails net::ERR_RESPONSE_HEADERS_TRUNCATED

I am trying to get a websocket communication working through a classic ELB with ssl termination to wowza, a java based media server.

Setup

VPC

R53
test.myTld.com 
IPv4, Alias=Yes, Target myElb, Routing Simple

CLASSIC ELB: myElb
listeners: SSL 64443 -> TCP 64443 : SSL Cert managed by AWS Certificate Manager (ACM)
security group [sg-xxxxx] : Custom TCP Rule TCP (6) 64443 0.0.0.0/0

EC2 
security group [sg-xxxxx] : Custom TCP Rule TCP (6) 64443 0.0.0.0/0

Non wss traffic is reaching instance as expected. When connecting to ec2 wowza using direct ip, the connection works and stream connects

wss://xxx.xxx.xxx.xxx:64443/webrtc-session.json

Frames = {status: 200, statusDescription: "OK", direction: "publish", command: "sendOffer",…}

However connecting through the ELB I get different errors being reported

WebSocket connection to 'wss://test.myTld.com:64443/webrtc-session.json' failed: Error during WebSocket handshake: net::ERR_RESPONSE_HEADERS_TRUNCATED

So following several tutorials & docs such as AWS ELB CLI I added the following

aws elb create-load-balancer-policy --load-balancer-name myElb --policy-name wowza --policy-type-name ProxyProtocolPolicyType --policy-attributes AttributeName=ProxyProtocol,AttributeValue=True
aws elb set-load-balancer-policies-for-backend-server --load-balancer-name myElb --instance-port 64443 --policy-names wowza

Confriming the policy has been updated,

aws elb describe-load-balancers --load-balancer-name myElb
"VPCId": "vpc-xxxxxxxx", 
"BackendServerDescriptions": [
 {
   "InstancePort": 64443, 
   "PolicyNames": [
                   "wowza"
                  ]
                }
            ], 
            "Instances": [
                {
                    "InstanceId": "i-xxxxxxx"
                }
            ], 

I then try a connection using the test.myTld.com & ELB, the first try reports

WebSocket connection to 'wss://test.myTld.com:64443/webrtc-session.json'
failed: Error during WebSocket handshake: Invalid status line

Frames = (Opcode -1)

then subsiquent tries report

WebSocket connection to 'wss://test.myTld.com:64443/webrtc-session.json'
failed: Error during WebSocket handshake: net::ERR_RESPONSE_HEADERS_TRUNCATED
Frames = (Opcode -1)

For what it is worth, here is the logs from wowza

server  INFO    200 -   WebSocketSession.create[94728968]   -   -   -   9432.997
server  INFO    200 -   WebSocketSession.destroy[926674790]: source:server status:-1 description:Unknown    -   -   -   9490.999

So my questions is what else do I need to set for the ELB to pass the wss headers to establish the websocket.