what I found is a typo in your control panel.
you had:
.gif,.jpg,.txt,.zip,.png,.doc,.xml,xlsx
Instead of
.gif,.jpg,.txt,.zip,.png,.doc,.xml,.xlsx
Note the period missing before xlsx.
I corrected it but I can't find your test post.
FYI,
In the ubb control panel selecting permission checks you have some fails that need to be addressed.