You should be able to see the challenged or blocked event under the Security tab → Events at Cloudflare dashboard for your zone and know exactly which security option was triggered. You can use Filter and URI path contains upload-plugin, otherwise use RayID equals the Cloudflare Ray ID from the bottom of the page (as on the shared screenshot is visible).
Once you find them, click on a particular one to find more details about it (user-agent, IP, HTTP version …). If yes, could you share some details which service was triggered that blocked you?
From the shared screenshot, as I guessed, it’s the Ruleset “Cloudflare Managed Ruleset” and Rule ending with “…5969e60b” (d93f48eb05324adbb47f0d055969e60b) which was triggered:
OK. I got it to work. I wanted a more generic rule and added my IP address. What was interesting is that I had to use IPv6. IPv4 did not work. Thank you all for your help!!!
Clients default to IPv6 over IPv4 if both are available due to the happy eyeballs RFC. When creating allow or deny lists both should be included because the Internet is a many varied thing.