In the local development fabric streaming messages works. But in Azure I experience many the problems. The reply message was “the HTTP request includes a non-supported header” and the resultcode was 400 – bad request.
I noticed that a small test on port 85 did work in Azure. The difference in portnumber I noticed after a while and was totally unexpected. Looks like there is an ISA server on port 80 that doesn’t allows streaming. Port 85 looks clear of these kind of checks.
Below some screenshots of fiddler (must have) of the blocked port 80 and successfull port 85 session


Edit: after consulting a colleague I used my phone to connect to the service (tether) and discovered that works without a problem. The ISA server must be in my company network. Using wireshark for capturing the traffic confirmed my companies ISA tampered with the headers so no streaming over port 80 was possible. Sorry Microsoft, my bad. But what header can be so bad that streaming stops working ….
Test application and uploadservice sources can be downloaded from here so you can test your (companies) network too.