Hi Tavis,
Glad to know you were able to find the cause of the problem.
To clarify one thing you asked in your original post, “BP_ScreenshotUtility_Base_C” is indeed the name of the internal UClass that unreal generated automatically for blueprint asset “BP_ScreenshotUtility_Base”. This is what is actually used by Unreal’s reflection system and other editor tools. Additionally, one of the things that is created for it is the CDO (Class Default Object) “Default__BP_ScreenshotUtility_Base_C”, a special instance which contains the default state of the class. New instances are created based on the CDO, and the “revert to default” button on Property Editors also rely on it.
By the way, also note that, if you re-save the assets that depend on the redirected packages and classes, their internal references will be updated, allowing you to remove the CoreRedirects afterwards if you choose.
Best regards,
Vitor