I think what's happening is that the PSN Store does not have the latest version of Goat Simulator. I have tried deleting and re-downloading the game and all the DLCs several times. I have tried downloading from the PS Library, as well as from the PSN Store. My guess is that because of this, I (and maybe others?) don't have the latest patched version, and thus payday is not being recognized by the base game.
When I go to "update history" on the game, it shows Ver. 1.02 in the log. When I go to the "information" on the game, it says Ver 1.03. This was updated and downloaded on Dec 14, 2016. "Check for update" yields no new updates available for download.
Is this Sony's error for not having the latest version (or patch) available as download?