If the network you're on is chatty or congested then the kernel might be dropping packets before pcap/seq can consume them. Are you seeing any network related messages in the SEQ console? Dropped packets? Failed decoding? ARQ give up?

If it's congestion related, you can try enabling session tracking and/or real time thread. You can also reduce what pcap has to sort through by specifying your IP or MAC address. (all of this is under the network menu)

If none of that helps then troubleshooting will get a bit more complicated.

Possibly related question - are you running Wayland on your FC30 install, or did you install an X server? As I understand it, Qt (and thus SEQ) isn't supposed to work on Wayland prior to Qt5 (and based on my limited testing, doesn't). I'm curious if you've had better luck with it than I did.