Many of the most common filtering issues arise because the staff have been assigned the wrong filter profile. It is very important that staff have access the STAFF profile as this allows downloads from untrusted sites (e.g. .zip files); allows access to some site which use only an IP address and not a full domain name and has a higher weighted phrase threshold for blocking than the student profiles do.
To check which profile is in use at any time browse to http://pleaseblockme.site while using Protex filtering and the profile is use is on the left hand side of the black bar below the orange heading and above the main body of the page.