This is not an issue related to my computer, customers have reported that it happens on their computers too. I’ve tested on 4.14.3 and 4.15.0 and there was the same problem on both versions.
You have Blueprint Nativization turned on? It’s still experimental in 4.14 so it might not always work. I suggest turning it off or try packaging with 4.15 once it releases since Nativized Blueprints are not considered experimental anymore in that version.
Yes, I have Blueprint Nativization turned on. With this post I want to report this error as a Bug to Epic, so that they can fix Blueprint Nativization so that it will work with my Marketplace asset.