I have just got the bellow error when I posted an answer:
I do not find the thread now.
I am guessing without any base that the thread was deleted. In this case we should get a message which make sense and inform us the issue and not general error. In other cases this might be a bug
bellow I add my response to if I will find the thread in the future I could use it:
Good day,
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It actually changed it for Office365
It is hard to know what you see since you used third party solution and did not gave us the information about this product/service, which probably could help anyway but at least will give a chance.
Regarding changes that mad in the O365 it is totally possible and probably normal, since O365 is actually Azure service and the users are Azure users (you can manage them in the Azure portal as well).
Microsoft redirects me properly to my IDP
This make sense and it is what I actually planned to tell you. If you are using third party solution then you should get their help. If needed they can contact the right person from the Azure team.
I am sry, but this seems like best option. We have no knowledge about the third party solution you use, and therefore my suggestions is the same as you already being told
If the third party company cannot help you then maybe they can come here and explain about their third party app and together you will fin the solution
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