I’m having issues with Microsoft Defender for iOS that I’m sharing here in case this may benefit others.

I think the root cause of the issue is that I have an EntraID account (production) and a Microsoft account (consumer) that are identical. One suggested solution is simply to rename the consumer account but I’d prefer not to do that if it can be avoided.

Here’s what typically happens:

My iOS device has Intune Company Portal App installed and I install Microsoft Defender manually from the iOS store. When I run Microsoft Defender I’m greeted by the screen above, which in this case only shows my consumer account.

The only option available is to sign up for a trial. This indicates that it doesn’t accept my production account which includes a license of Defender for Endpoint.

In other cases, I’ve see both my production and consumer account listed but it never seems to accept my production account when my consumer account is also present.

Interestingly, I get different results depending on whether I use an iPad or a iPhone.

On my iPad, I noted that I had both my production and consumer credentials in the Microsoft Authenticator app. I removed all the credentials so there was none. I reboot device, added ONLY my production credentials to the Microsoft Authenticator and then I was able to login to Microsoft Defender with my production account. Interestingly, this worked for a few days and then I had to repeat the process to get Microsoft Defender on my iPad logged back into my production credentials again.

The story is a little different on my iPhone. I didn’t want to remove my Microsoft Authenticator app but I did remove my consumer credentials from the Authenticator app, leaving just my production credential there. Even after a few reboots, I still wasn’t able to login to Microsoft Defender with my production account. Instead I logged into Microsoft Defender using a demo M365 E5 account I had. That allowed access and Defender was working.

A few days later, on my iPhone, Defender was asking for a login. I was now able to login with my production account and enable Defender correctly. However, I do notice that when I run Defender on the iPhone I see it switch out to Microsoft Authenticator and then switch back, as though it is checking my account. Since I have just managed to get Defender logged in on my iPhone with my production account I’ll need to see whether it ‘sticks’ or whether it prompts me to login again in the future.

In summary, as I said initially, the root of these issue come down to the fact that I have the same consumer and production identity and it seems Defender on iOS can’t differentiate. It also seems that Defender on iOS also interacts with Microsoft Authenticator in some way, also in different ways on an iPhone and iPad.

I’ll post more when I have done further testing.