phenominam

I've been trying to record external MIDI notes into Logic from my Prophet 08 synth then record the audio later, separately. But when I send the recorded MIDI back into the Phrophet to record the audio, it changes the tone of the patch every time as soon as I click out of the External MiDI track. It sounds almost like the Prophet patch tones are pitched up an octave or like a high-pass filter is applied, but there is no processing or effects happening in Logic and I've never tried having Logic manipulate the Phrophet's parameters and it never used to do this. Any idea what the problem is?