If you got your Player from the App Store, it will be version 108.15 (v10815).
Did you download and install "Optional Download - AppGameKit V108 BETA 15" or "AGK Windows Installer - v1076" from your TGC 'My Products' page?
If you installed v1076, it is not compatible with v10815.
If you want to keep working with v1076, you can download a working v1076 Player from
this page. I built that Player (and the site it is on) and many have used it without issues.
Cheers,
Ancient Lady
AGK Community Tester and AppGameKit Master