You should try to have your drums on a single track and if you can merge all events/regions to a single one. If you have an option like "Use MIDI file type format 0" when exporting your midi file from your program enable it! If you can't hear parts or all your drums after re-importing please check your drum library if it is receiving on all midi channels (omni), also see the FAQ about omni channel in Kontakt.
Select your midi region(s) -> Right click your region(s) -> "Bounce and Join" -> "Join" (will make your life easier when re-importing the converted midi) -> Right click your region -> "Export" -> "Export as MIDI File" -> "Save"
Select your midi event(s) -> Right click -> "Event" -> "Export Selection" -> Choose filetype ".mid" (NOT ".musicloop") & "Save"
Select your midi drum track -> Click "File" -> "Export project MIDI" -> Choose option "Selected Tracks only" -> Choose option "Merge to single MIDI track (type 0 MIDI file)" ->"Save"