MPC one as Midi Sync slave - recording is off

Hello,
I am trying to sync the MPC One (latest OS) to a Workstation-style synth Arp/seq. The sync works, the MPC runs in timing with the synth. But... I can not record audio as soon as I activate the sync´ing. As a Master it works, but not as a slave. Audio recording can be switched on, the external source can be heard, but as soon as I start recording, the red Rec switches off. What´s wrong?

Hi there, I found a video on YT that describes the same problem:
https://www.youtube.com/watch?v=2yjO8COTdTk

Even without external sync, if you change the (MPC's master) BPM while recording an audio track, the recording will stop. It seems that it is not possible to change the BPM while recording. (With external sync, the BPM always changes very slightly.)

Hm, well I did not really change it - maybe I did when you consider the clock signal as "change". I am not home now and can not check what happens if the MPC was set to the same speed - if that makes any difference. But I will try when I come home.
Ok, maybe I will have to accept recording does not work as slave. Thanks for the answer.