Back in January, I discovered a family where the children had been duplicated using different spellings of the last name. So, I found birth records on FamilySearch.org for each child with the correct spelling of their last name and copied the citations to each profile.
This morning, I discovered that all of the merges had gone into default approval status, so I started putting through the merges. I needed to double-check something on one of the profiles, so I clicked through to the FamilySearch record, and got a 404 Not Found message.
This prompted me to check the rest of the children, and I discovered that each and every birth record I had cited is now missing from the Massachusetts Births and Christenings, 1639-1915 index.
I've submitted a problem report to the support email @ FamilySearch, but I'd be interested to hear if anyone else has had similar problems.