Presets not showing on VSTs

on qtractor these preset lists are only the ones you define your self under qtractor premises and while using the native/generic plugin UI; exception is for LV2 plugin state presets, which will get listed there whether defined under qtractor or else.

on VST2 plugins in particular, you may even load .fxb and .fxp files and there define custom presets for your convenience--but remember that you must always use the generic plugin editor form for just that (as in rclick > Properties...) to manage those local presets; the internal VST plugin presets are not, won't ever get there listed, mind you: you'll have to go the the proper and genuine plugin's GUI editor for just that, so sorry.

otoh. if you're talking about "programs" as they are also called "patches", selectable via MIDI bank_select+program_change messages,
nb. "programs" are usually and quite often confused as "presets", but not conceptually the same, as for instance, VST plugin presets do often provides one or more, multiple "programs" ...

now, for selecting "programs" (and not "presets") you must go to a Track Properties dialog and select the nominal Instrument you're after (ie. the VST plugin there is); and then select the desired patch aka bank+program; afterwards, you may also have this on the menu: see Track > Instruments... (and not Presets whatsoever).

hth.
cheers