There have been a few problems lately that have been caused by Windows Defender. Please take a look here:
https://yabb.jriver.com/interact/index.php/topic,114101.0.html
Just browsed thru what appears to be a very thorough Defender link. From what I see, one would need to make programming changes to Defender which I am not comfortable doing. I am a MC user, not a programmer. Even tho' the tutorial is "Betty Crocker", I do not like to follow instructions and make mods that I do not understand.
Couple of additional pieces of information... I have been successfully using MC on this new machine for several months without issue. When I exit and reopen MC, it has successfully done so with all albums and artwork showing. I have manually imported over a 100 folders/albums without a problem.
In addition to cover art being replaced by blue music notes, I have learned that clicking on the album results in an error message that the album cannot be found!
The album artwork is created in one or more ways:
1) Generated by EAC during the ripping process;
2) Already part of the downloaded folder/album and displays when the folder is imported;
3) Is artwork found on the web by me and stored in the folder which must then be pointed to using COVER ART option;