saguaros
Save is not the problem. I removed one of the custom filter and it was removed without any problem.
Try it yourself. Remove a custom filter and save... yes the 401 page will showed but the filter is saved correctly and you can check it seeing the change in the front-end page.
You think is a Firewall problem? Ok, i'm reinstalling site in localhost and make a try for you.
EDIT:
Problem found! It is not the firewall but the htaccess credentials. I temporary disabled it, change filter options and save. This is a workaround but clearly a fix to your extension is needed. Other extensions works well with htaccess credentials too.
