SSG, also known as Supercritical Simulations Group, has recently released a hotfix for their 747-8 Inter Anniversary Edition addon for X-Plane 11. The update mainly features a fix for the sound plugin in the aircraft, but also compatibility with X-Plane 11.50b9+ while still with X-Plane 11.41.
Primarily the update is focused on the DreamEngine sound plugin so that sounds are now working properly.
The very same update has been also released for the SSG E-Jets series, also for X-Plane 11. Both updates can be downloaded via the SkunkCrafts updater.
If you want to purchase the 747-8 Inter Anniversary Edition, you can do so via the X-Plane.org Store for $48.75 $65, and if you want to purchase the E-Jets, you can do so for $33.75 $64.95