Hello, I am also encountering this error, already did change max_input_vars on settings.
Console error shows this:
Uncaught SyntaxError: Invalid hexadecimal escape sequence (at admin.php?page=wc-settings&tab=woof:5347:31)
jQuery.Deferred exception: woof_ext_custom is not defined ReferenceError: woof_ext_custom is not defined
at HTMLDocument. (https://localhost/dcpi/wp-content/plugins/woocommerce-products-filter/js/plugin_options.js?ver=1.3.3:603:5)
at e (https://localhost/dcpi/wp-admin/load-scripts.php?c=1&load%5Bchunk_0%5D=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-mouse,jquery-ui-sortable&ver=6.2.2:2:30158)
at t (https://localhost/dcpi/wp-admin/load-scripts.php?c=1&load%5Bchunk_0%5D=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-mouse,jquery-ui-sortable&ver=6.2.2:2:30460) undefined
Uncaught ReferenceError: woof_ext_custom is not defined
at HTMLDocument. (plugin_options.js?ver=1.3.3:603:5)
at e (load-scripts.php?c=1&load%5Bchunk_0%5D=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-mouse,jquery-ui-sortable&ver=6.2.2:2:30158)
at t (load-scripts.php?c=1&load%5Bchunk_0%5D=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-mouse,jquery-ui-sortable&ver=6.2.2:2:30460)