Figured out - what was going wrong. 
Seems like there are 2 sections to the frames, one's a table and below one is a descriptionViewer or alike.
Unfortunately, the above section had 0 height, giving the illusion that the table is empty.
May be we can disable allowing the user making the height of the table 0, or showing it in some way so that he knows that there's table. 
Suggestion : Use left-right alignment, table on the left and then selecting a frame shows it's connect on the right.

Unable to reproduce the issue on Mac 10.12.4 using chrome reported version-58.0.3029.81, stable-58.0.3029.96 & latest Canry-60.0.3093.0 as per the below steps:

1. Navigated to above mentioned URL in comment#0.
2. Open Devtools
3. Click on 'Network' tab
4. Reload the page
5. Click on 'WS' tab under 'Network' section
6. Click on 'echo.websocket.org'
7. Click on 'Frames' section
8. Observed frames are displayed for the selected websocket.

Please find the attached screencast for reference & let us know if we miss any steps to reproduce the issue.
If possible , it would be more helpful if you provide us the actual and expected screencasts of the issue to triage further.

Thanks in advance..!!

Deleted: 716884.mp4 1.2 MB

	716884.mp4 1.2 MB View Download

I was going to report this as a "bug" also but once I moved my mouse over the columns "Data, Length, and Time" I realized that there was a vertical splitter and I had to drag it down to see the frames.  This is more of a UX issue and I think that it should be made more clear to the developer if the frames view becomes not visible. 

Thanks, we have some love coming to this area in some future patches. I'm going to mark bug as fixed to get it out of my queue.