I am using SignalR with Server Sent Events on my site and I was able to debug that pretty well in Chrome using the developers tab by clicking on the request and then selecting EventStream tab.
But recently something weird has happened, every time I chose the request with EventStream tab the selection "jumps" after a second or two to either next or previous item, so I cannot really see anything. Another strange thing is that even if I close the console, next time I open developer tools, the console pops up again on it's own. I don't know if these are connected, but it did not work like that before, so perhaps it's same type of problem. My version of chrome is: 49.0.2623.87 m, but I don't think I did the update right before it happened.
This seems to be related to the open bug here: https://bugs.chromium.org/p/chromium/issues/detail?id=592911
As they suggest as a workaround, and which works for me too, is to filter your network tab down to only that one item, so it cannot jump to a different one. For me filtering "connect?" works to show only the connection with the EventStream.