Saving the subscription settings creates a 403 error

When I attempt to make changes to the ‘subscription-ui settings’ section of the settings page, as well as when I try to create a new subscription page and save, I receive a 403 error and the changes do not save.
Any advice on what permissions I can change to correct this?

I do not receive the same error when I try to save any other section of the settings page, only ‘subscription-ui settings’

Thanks in advance.

@dvon Possibly caused by anti-malware software on the web server. See this earlier topic Unable to save new Subscribe page - #2 by duncanc

That was so simple it’s frustrating I didn’t find it earlier.
I was able to disable ModSecurity through the .htaccess file in /lists/, save my changes, then re-enabled ModSecurity.

Thank you @duncanc for pointing me in the right direction.