Empty tracks with bleep during export

I have this really strange bug and it started this morning and I don't know how it started. It's in PP2015 CC and AME 2015CC not in the 2014 release of those programs

When I export a sequence with 18 track of audio but not on all off them is audio like you see below:

Image may be NSFW.
Clik here to view.

I get bleeps every second (like a countdown clock) on the empty track. If a fill the empty track with a tone clip and set that to 0 (no sound) the export is correct.

Who has an idea what happen and how can I solve this problem?

Thanks.