I got the following error when trying to execute actions against Exchange online using the MSOnline module. Specifically when trying to call Set-UserPhoto. The production site we ran this against uses ADSync so I assumed it was something to do with this, as my testing worked perfectly in my demo environments. We searched google for ages and couldn't figure it out.
After about 2 hours, this had magically fixed itself and the script has run fine ever since. Unsure what happened, but try waiting for a while to see if it resolves. ADSync wasn't new to the organisation so it wasn't as if data hadn't been synced.
Recipient "xxxxx" couldn't be read from domain controller "xxxxx". This
may be due to replication delays. Switching out of Forest mode should allow this operation to complete successfully.