unable to save settings

I’m not sure exactly at what point this started, but I’m working with a site that’s only been setup within the last 6 months, and the add-on had no trouble at that time. If I try to save my settings in Insert Headers and Footers I get “403 Forbidden Error Page” and my IP address while all other add-ons (I only have a handful running, including Yoast SEO) and Bulletproof Security. It’s a real problem because I have code inserted by the add-on in the header and footer that I need to update, and even clearing the content doesn’t have any effect on my ability to save. I would guess removing the add-on will allow that content to be removed, but I still want to have the ability to insert code using the add-on. Any suggestions?

https://www.ads-software.com/plugins/insert-headers-and-footers/