When importing the Vecna: Eve of Ruin megapack into a campaign, it does not appear to contain all of the content that has been created for VEOR. The sound packs seem to end at The Dragon’s Pride, and so does not include the content for chapters 9-11 / Part 5. When I search the player, it does appear that there is content from these chapters, so it just appears to be the Megapack. Part 5 also shows up in the store, just not in the megapack list.
(Side note: I have used Syrinscape for years, and was not aware of this feature until Ben posted a video showing the process a few weeks ago.)