Only Microsoft would give you an online sync tool which won't let you save filenames that include characters which are DEFAULT in many cases (i.e., saved web pages all include a folder which ends "_files". Renaming this breaks the saved web page irreversibly (you can change the name of the file and associated flder by changing the saved .html file, but that does not change or remove the "_files" at the end!).
Only Microsoft would give you an online sync tool which won't let you save filenames that include characters which are DEFAULT in many cases (i.e., saved web pages all include a folder which ends "_files". Renaming this breaks the saved web page irreversibly (you can change the name of the file and associated flder by changing the saved .html file, but that does not change or remove the "_files" at the end!).