so you are saying you get 8 voices when connect via device port (e.g. usb keyboard) but not when its connect via the host port? and does the patch stop playing, or your disconnect the UI?
well if the patch is 'right on the edge', then these is a possibility of any extra processing could 'tip it over the edge'
midi din vs midi device vs midi host are all slightly different code lines, or perhaps your LPK25 is sending a few more messages, at a higher rate?
if the UI is just disconnected, sometimes this can happen due to a little extra load when the patch starts, which means the UI times outs, but the axoloti patch itself is running fine.
all that said, Ive not had a chance to play with this yet, so the above are just ideas.
generally, Id say, always leave a little headroom on patches... as even if they work today, there is a possibility a firmware upgrade in the future might 'tip the balance'.
of course the opposite is possible that future versions are more efficient, so you will gain some headroom, to play with later, and that point you can add more voices.
but thats just the way I would play it...