Transactions from some remote hosts polling one of my websites that is using Cloudflare are failing to get a response - triggering a page with “Please wait while your request is being verified…”.
A similar issue is described in community discussion as being related to Cloudflare caching, but none of the conditions for the issue there apply to this case - specifically the website is not using the “Cache Everything” page rule, nor setting and Edge Cache TTL.
The requests causing the issue are innocuous - one is to poll domain.com/actions and receive a JSON packet in response, the other is to poll the domain with a query appeneded (e.g. domain?variable=value) along with a POST packet (again triggering a json response).
Other servers polling same location do not see an issue: so far I have not identified a specific characteristic of the servers with the issue though the response to the similar issue noted above may indicated that the servers are running some kind of common firewall system.
Does anyone have any thoughts about what might be causing the issue and / or what I can do to mitigate (other than remove the website from Cloudflare which I am reluctant to do)?