Just for double checking, I copy the following instruction directly from the comment section of the “BackToTop.css” file. May not be relevant to your case but won’t hurt anyway. As for me I use this function on a daily basis and it still working fine currently.
To use this function:
1. first put a " ^Top" as an anchor at the begining of the page (exclude the double quotation marks)
2. then put “[[#^Top|TOP]]” at the end of the page (exclude the double quotation marks)
** As for the " ^Top" anchor, remember there’s a space before “^” ("[space]^Top")