First saw the issue with
http://www.fanfiction.net/s/7251431/1/. I later updated an
anthology (AO3 series) that added a new story, single chapter with no problems.
I then updated a
second anthology, also an AO3 series, but the update was to add a new chapter to one of the fics in the anthology, again with the same error message as above.
For the latest single story updated with that error, a yellow pin icon is shown in the normal records view (see attached screencap); not sure why it should.