Hi, I have deactivated HMWP plugin and also removed all HMWP rules from htaccess file (installed WP htaccess editor plugin), but still I’m not able to publish any page. So issue seems to be something else.
You mentioned above that if you rename htaccess and create a new one, then you can publish page. Can you please let us know what that new htaccess contains? May be you can try activating HMWP plugin when this new htaccess is active? (currently HMWP is disabled).
Let us know. Thanks!