I’m running OS X 10.4.11 as well. I followed your steps and it works fine on my system.
How are you importing the midi file ?
EDIT: Could you tell me more about the midi file your importing ?
EDIT: Maybe I can try to replicate the midi conditions your importing…
EDIT: Also, what are your midi import preference settings ?
EDIT: I’m testing it on version 2_5 RC1
1 -> Renoise will also import tempo automation form the MIDI files, if present. This always overrides the current transport BPM.
2 -> Place the cursor on the mast track, then insert a new track. This will add a new send.