Well, the photo of this 'new' 9cM match has definitely come through before, and I've checked the other sites I use to make sure I'm not remembering it from there. I've also done a search on the name and it doesn't come up - as usual for the first 24 hours of a new match coming through (it doesn't seem to get indexed immediately) - and so it's not some kind of glitchy duplicate.
If Ancestry has removed a load of matches for some reason, even if by mistake, they're hardly likely to admit it, especially if notes and colour coding have been lost with them.