The following are common problems and solutions to fix them.
Do you use Cloudflare or cache your website?
Redirection uses the WordPress REST API, and your site may have disabled this.
Wordfence or other security plugins can block WordPress requests.
Sometimes other plugins can interfere with Redirection
There are many reasons why a URL may not redirect.
There are many reasons why a URL may still redirect.
What version of PHP does Redirection support?
What to do when data is not saved, or an upgrade repeatedly fails with a loop.