Can you please look into this glitch. Thanks.
Best answer by Mathis
This is to inform you that our engineers have been able to locate the root cause of this issue and have put a fix for this into place. Despite the fact that similar issues of this nature have occurred in the past, this particular bug first occurred at the end of May 2018.
It is now possible to add tracks to your playlists again, and tracks that were in your playlists before should no longer disappear. Unfortunately, it was not possible to restore any tracks that have disappeared from a playlist due to this incident.
Our sincere apologies about the inconvenience and thank you for hanging in there.
All the best