/testimonial 404

Currently using version 3.0.3 of the Testimonials Widget plugin. The Testimonial Page URL returns a 404 error. I have checked the knowledge base and performed all 3 recommended fixes. They have not worked. The archive page URL is working and the individual testimonial URLs are working, but not the Testimonial Page URL.

https://ww.wp.xz.cn/plugins/testimonials-widget/