Hey there, sorry for not getting back but we have released 4.0.1 just yesterday and it should solve or fix your issues. It appears the problems have arisen from a very odd, non-reproducible bug when using lock tracks in your song, we were able to see that the metadata had not been implemented as expected and your wav file was in the wrong place causing the crash when Aeros couldn’t find it.
I would strongly suggest creating a new song, it may be this original version of your song was corrupted somehow in the case you do not see it getting better.
I would also suggest not using or renaming the Song_1 file on the Aeros, there are some sticky bugs we have to squash dealing with song_1
Thank you for getting back!
Please let us know if this new version does anything positive for your experience or solves the issue entirely (hopefully), we apologize for any inconvenience!