It has been reported by some users that they had tried to attach a file (i.e. 17MB rar file) and although they saw the success message, the file was not uploaded (checking the attachments' folder). The same users are able to attachments at other occasions, so maybe it is not a browser extension or software they use.

I have not been able to reproduce the issue, having uploaded (as a registered user) larger files of the same type.

Has it been observed by others? Any ideas as to why it may be happening?