A4 Arp via ext. Sequencer PGM Change

Hello. I recently made a Track where I use the arp from the A4, the notes are triggered via my ext. sequencer. Everything works fine so far. I collect many songs in my sequencer and work with pgm. Changes.

If i now jump to the “Arp Song” the arp Sound on the A4 get really strange, noisy …
If I start the “Arp Song” but have the Arp Pattern not played from the beginning, start the pattern later, evything is fine.

Hopefully somebody can help
Thx