@EssexGeoff Thanks for the pcap file. There is nothing wrong with the file, as it is showing data in the source/destination/protocol columns. So it must be something in your wireshark settings.
You can delete your current preferences by opening the "About Wireshark" menu item (under Help on Win/Linux/*ux, or uder "Wireshark" on MacOS). Then go to the "Folder" tab and double-click on the entry that says "Personal Configuration". Once that folder is open, close Wireshark first and then delete all the files in the personal configuration folder (you can leave the plugins and profiles folders if you like).
Now reopen Wireshark and load the file again, the columns should now be populated...
Did you slice the packets to only 34 bytes or less? What do you see? Can you share a pcap file? It's really hard to see from here what you are seeing ;-)
Thanks for the prompt response! I am new to to Wireshark, but hope this will help explain: https://www.dropbox.com/s/a6t9al1r4ul...