This is a call for some debugging and test assistance. If the following makes no sense to you, nevermind! It is only a problem for some premium themes, which is way I’m asking for help.
If you have experienced the long-standing problem with the the Team Rosters plugin messing up the Featured Images (aka “Thumbnails”) for posts on your site, I MAY have found a fix. If you would like to try it out, you can download it from the plugin’s development tree. You only need the mstw-team-rosters.php
file. If you do try it out, please let me know how it works on your site.