I ran into this bug while messing around with my DAW and post this in hopes it may help somebody else.
On Fedora 38, qmidiarp will crash with a failed assertion if you attempt to add an LFO or sequencer to the program (both standalone and LV2). A workable fix is to rebuild it without stack protection, either just run configure/make/install yourself if you want it outside of package management, or use this spec file to build an RPM if you want package management niceness.
This spec builds against pipewire-jack-audio-connection-kit-devel rather than jack-audio-connection-kit-devel, which is what you probably want if you're running Fedora (since jack-audio-connection-kit-devel will force the removal of pipewire-jack-audio-connection-kit). Or just built it in a container against jack if you want.