Adding album artwork to custom music files in itunes (Windows)

I have a vinyl record player connected to my computer and i use audacity to record the vinyls and create music files to save on my computer and I add them to my itunes account so i can listen to them on my phone. When i am viewing these songs in itunes i can create an album and add these songs to it. Question is, can you no longer add your own album artwork to your own music files that you uploaded to itunes manually? When right clicking on one of my custom albums then clicking album info, then clicking on the artwork tab it gives me the option to add album artwork but when i add a photo from my computer nothing happens. It gives me the option to upload album artwork, but when i select the photo i want to use and click ok, it just doesn't add the picture, nothing happens. I can, however, add this exact same photo to any album that i downloaded from the itunes store. So any music form apple that i downloaded from the store gives me the option to change album artwork and it works fine but when ever i try to change the artwork of one of my custom albums i created, it doesn't seem to work. Also, when right clicking on a specific song (one i created using audacity) in itunes, then clicking song info, then clicking the artwork tab, the add artwork button is grayed out and doesn't give me the option to change the artwork at all. I am using windows 10 and the most recent version of itunes per this current date. If anyone has run into this problem as well please share, if anyone knows a fix for this problem, I would greatly appreciate the help.