If you are systematically getting a challenge or captcha page in the admin section of your site, chances are that you are a customer on a paid Cloudflare plan and the Web Application Firewall (WAF) comes into play. The solution finds in the Cloudflare Firewall app.

Either:

1. Turn the Security Level to a lower level under the Settings tab.

Or:

2. Whitelist your IP(s) in the IP Access Rules found in the Tools tab.