I agree with you OP, this does seem like it's an issue, rather than simply being "because it's linked to Heavensward" as the other posters seem to think. From what you described, the bundle basically gives you three downloads. One is the game itself, as though you bought just ARR from the store. The second is Heavensward, as though you bought just that from the store. The third is the theme, which is over all unconnected to the other two for this purposes. Because PSN sets up multiproduct downloads in this way, one doesn't interfere with another, and thus the Heavensward part of this shouldn't be affecting you ability to play ARR any more than it does other players who have just purchased ARR from the store.....

As for a fix, you can try the obvious, such as turning your system completely off and back on, (not just putting it into rest mode). You could also try either checking for updates through the PS4 itself, by pressing the "Options" button and selecting "Check for Updates". If that doesn't work, then the only solution I can think of is to delete your download of ARR, and try redownloading it. It's always possible that a system file wasn't downloaded properly, and is causing this bug.....