I apologize upfront if this becomes a little convoluted.
First, I was mistaken about the sequence of events required for the bug to appear, and what causes it to "fix itself". I get the wrong ratings if I reload the game and immediately move on to the Roster screen, or the Lineup screen, and I'm assuming any other screen that shows ratings. Going to the Game Settings screen *at all* is what fixes it. Checking and unchecking the checkbox was a red herring.
To hopefully guarantee perfect clarity about what the issue is and how to make it appear, I made a 36 second
recording with OBS Studio.
I was able to reproduce the issue in a fresh MLB standard game. I now have two save files instead of one in which the issue occurs, and changing between them doesn't affect it. I uploaded the new file as "Silfir_April_2019.zip" as per the instructions, provided I understood the instructions. (The reason I didn't upload the original league file was that I mistakenly assumed I had inadvertently fixed some sort of league file corruption for about ten minutes, and tried to make it happen again.)
I hope this helps narrow it down somehow. If you don't get the issue on your end, I can only imagine it has to do with file permissions or something.