Left and right channel are swapped initially

OS info

Version of Volumio: 3.212
Hostname: volumio
Kernel: 4.4.154
Governor: performance
Uptime: 0 days, 7 Hrs, 22 Minutes, 10 Seconds

Hardware is a Rock64, with the Rock64 ES9023 audio POT port. Output via analog into an Ifi Zen CAN.

When I play music from my DLNA Server, and I select a song, left and right channels are interchanged when it starts playing. After I press the |< Back Button, ist starts playing with the sound coming from the correct direction. This is consistent and happens every time. Also with different audio formats (ogg, flac, …). I’m not sure , but when the channels are swapped, the sound also may be out-of-phase. But I’m really not sure about this.

Any ideas where this might come from?
Best Regards,