This is kind of a bug that I've seen sometimes that the UI shows Remediation failed but actually deleted the sample. This is nothing to be worried about and I've not noticed this in the last couple of months so maybe the bug is fixed. And the 0 kb file used to happen a lot to Norton which they have only fixed very recently and this is the first time I've seen this for Windows Defender. Anyway again, nothing to worry about as everything was deleted.