Gmail settings being blocked, even with blocking disabled

[Blackbat]

I've been running Pi-hole on my Raspberry Pi hardware successfully for a long while but have recently seem some strange behaviour with Gmail. I don't normally use the Gmail web page, preferring to use Outlook with my Gmail account, but I needed to go into Gmail settings to make a config change and the settings "cog" icon on the webpage was greyed out. I refreshed the page a few times and looked in the Pi-hole logs for anything being blocked but nothing was showing, so I disabled blocking for 5 minutes and the problem remained. If I change the DNS settings on my router to point to Cloudflare DNS then the issue goes away, so it appears the Pi-hole is indeed blocking something even when blocking is disabled. It isn't just the settings cog either, the Pi-hole appears to be blocking the gmail web page when authenticating any 3rd apps, such as Outlook, to access my Gmail account.

Many thanks for any suggestions on how to resolve this. I'm using a Chrome browser but have also tried Edge with the same result.

Debug Token: https://tricorder.pi-hole.net/yGKkgi0d/

[jfb]

@Blackbat

I disabled blocking for 5 minutes and the problem remained

If you disable blocking and the problem remains, Pi-hole is not blocking anything that is causing this problem.

Perhaps the upstream DNS server you use for Pi-hole is not resolving the domains needed?

Use these tools to help with troubleshooting:

How do I determine what domain an ad is coming from?

Block ads or fix broken sites This FAQ is written in the context of finding out how to block an ad that isn't blocked automatically, but the same steps can be used to troubleshoot issues with sites that don't function properly. An example is that sometimes certain payment gateways try to collect metrics on the sale, but these domains are blocked by Pi-hole, so the payment cannot be processed. Also, some links send you through several referrers and if one of them is blocked, you may land on a …

[Blackbat]

I've got Cloudflare configured as my upstream DNS on the Pi-hole, and if I configure my router to use Cloudflare, or my PC to use Cloudflare directly, everything is good. I've tried the tools in the link above to see which domains are being queried, but as far as I can tell none of them are being blocked. It's all very strange, especially as it used to work.