“What's happening is that some games show that you have them purchased, but you actually can't download them from the Library section. You have to use the PlayStation Store app, the web browser, or the Playstation App to actually download these purchases,” explains one of the affected PS4 owners on NeoGaf.
The issue doesn’t appear to be widespread, but there have been other reports of this happening after other updates too. There’s likely a solution:
1. Go to the PlayStation Store. Find the missing game and see if you can re-download it.
2. Check that your PlayStation Plus subscription hasn’t ran out, as the game could be linked to it.
3. Restore licenses by selecting Settings > PSN > Restore Licences
4. Deactivate your PS4 as your primary console and reactivate it as your primary PS4. Do this in Settings > PlayStation Network/Account Management > Activate as Your Primary PS4.
5. Reboot your PS4 into Safe Mode and rebuild the database. Hold down the PS4 power button until it beeps twice to boot up into Safe Mode. Choose option 5 to rebuild database. This could take a while, and you should only do this as a last resort.