@btacke Are you on Linode? Go through your 365 Support, not generic Microsoft support.
I ended up figuring out it was an issue between my cloud service provider (Linode) and Microsoft.
The delisting address didn’t work and neither did using sender.office.com. I had to go through Office 365 Support to get the IP address delisted.
@btacke I hope this helps you as well!
Thanks
I am having this same problem that started at approximately the same time. The same situation where it works on other websites but not one specifically.
