Hey there,
this is caused by a known issue where Aeros is expecting track 1 to be used when saving.
We made a quick fix which is available on 4.2.4 which is available as a beta but will soon be on wifi.
Im that version, the Aeros will move the audio recorded on track 2 over to track 1 if it is saved and track 1 is still empty.
Thanks for reporting!