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 is found in the Cloudflare Firewall app. Either:
1. Turn the Security Level to a lower level under the Settings tab.
2. Whitelist your IP(s) in the IP Access Rules found in the Tools tab.