I'm not sure, but I think you might have left out a "not" near the end of that. (Because "there are some X which are Y, but this X is not one of them" is a pat

I'm not sure, but I think you might have left out a "not" near the end of that. (Because "there are some X which are Y, but this X is not one of them" is a pattern I recognize as common, and "there are some X which are Y, but this is one of them" is not a pattern that I am familiar with)