Let me see if I can explain this...
You are the ONLY person who can see and edit the profiles you manage for LIVING individuals because they are privacy locked. On those profiles you see a big black "lock" icon on the upper right of the profile. There is no way for anyone else to be removing sources unless you have allowed them access to do so. There is also no way for anyone to look at the profile to see the reason you have "disappearing sources."
Herb, Barry, Marion are trying to tell you that you may have made an error in how you did some formatting so the sources are not showing after you save the profiles and look at the finished bio even though they are still there in the "edit" mode. The most common reason this would have happened is if you used inline citations and lack these lines below the biography:
== Sources ==
There could be other reasons, but no one can look at your profiles for living individuals until you allow them to.
If you want you can temporarily put someone else you trust on the "Trusted List" for the profiles on which the sources are disappearing so they can examine them. You will need to have that person's email address to do that. You can send a private message to anyone you wish to see if they will provide you their email address if you don't know it. Once you have the email address you will click on the "Family Tree & Tools" tab for the profile on which you have a problem, scroll down to and click on "Trusted List." On the next page, scroll down to "Add to Trusted List." Once on the "Trusted List" your selected person can see and/or edit the profile.
Until then, no one can help you figure out the problem on your privacy locked profiles for living individuals.
Herb asked you if the same problem was happening on any profiles you have for deceased individuals on which the privacy is "open." These will have a green lock icon. If so, provide the profile ID of at least one of those profiles here and someone will examine it.