Windows Defender

Ideally there should only be one vendor's Internet security product installed on a PC at any given time therefore it's best to disable Windows Defender if you're going to use McAfee however that probably wouldn't cause McAfee to behave as it is.  If this is the McAfee provided by us I suggest contacting their support directly at 888-556-0959 as how they would be better able to assist.

I've always had two firewalls installed on my computers:  Windows Defender and (Symantec or McAfee).  A firewall controls ports and blocks malware.  Since all firewalls won't catch everything from the Internet, two firewalls add another level of protection.  There shouldn’t be any problem with both programs blocking the same thing.

However, the only problem with two firewalls...which are now bundled with anti-virus program as security suites...is if both anti-virus programs try to remove the same virus at the same time.  A computer can lock-up if two programs fight over same file.  I prevent lock-ups by disabling real-time protection on one program and scheduling their scans at different times.

I've seen your issue on my computers.  McAfee warns my computer is "at risk" and halts its scan.  This happens when my computer has been turned off for a week or so.   When I boot after a week; the programs download their latest update and catch up on missed scans at the same time.  This often leads to McAfee thinking Defender is out-of-date.  Sometimes my Microsoft Windows updates will add to the quagmire.

If you wait for Windows Defender to update and scan, McAfee will soon normalize.