Problem playing back imported MIDI in 10.5.1's Sampler

Hi there,

I'm on Logic Pro X 10.5.1

I've just started working with the sampler and have built an instrument that I'm happy with. I want to import a MIDI track made in Sibelius (which I have done many times in Logic and it has worked fine) but I'm having a lot of trouble with it when using the sampler instrument.

I want my newly built sampler instrument to play back the MIDI information. When I import it and drag the MIDI data into the aforementioned sampler track, not only can I not hear anything play back but now the sampler is left unresponsive even when I press keys on a MIDI keyboard when the track is armed (this works and I can hear it up until the point of dragging the MIDI data into the track and then immediately stops working). If I change the instrument on the track from the sampler to another Logic software instrument (e.g. Retro Synth) then I hear the imported Midi play back correctly. I can't understand what I'm doing wrong. It's also worth noting that when I have the sampler instrument open and play back the MIDI data, I can see instrument is detecting the MIDI impulses as the pitch tune wheel in the synth dialogue of sample blinks in the rhythm of the imported MIDI.

In Sibelius I export the MIDI file as MIDI type 1. The MIDI channel on the sampler track in Logic is set to All. I also tried just opening the MIDI file directly with Logic and then loading up the saved sampler patch afterwards, but this doesn't work either.

Any ideas where I might be going wrong? Tearing my hair out & feel it's pretty likely I'm missing something really simple.

Thanks in advance!

Matt