Issue with MIDI Fluidsynth Plugin Repeating Notes

A strange phenomenon is occuring that I’ve searched around for but have not quite found an answer to:

With certain soundfonts, if I host Fluidsynth and connect to the MIDI Input for Fluidsynth from something I might have already recorded or something coming in from a MIDI controller, through Ardour, I get totally normal and expected behaviour.

However, if I try to use the Fluidsynth plugin, I get this strange tremolo effect where the note seems to repeat at a frequency that is correlated with the frequency of the note I’m playing (so lower notes take longer to repeat and higher notes repeat faster). I tried turning off things like reverb and chorus and there are many soundfonts where this doesn’t happen, but I’m a bit interested as to what could be happening here as it would be nice to manage fluidsynth via the plugins instead of having to always host it on its own.

Thanks