Should we at least put a line or 2 in the manual stating vulkan is only experimental?  Also should we change the option in Settings->Preferences, Performance tab from "Vulkan" to "Vulkan-exper."? Maybe someone will try it and be able to suggest some fixes. 
It worked previously when I tested cin-12-02-2026-x86_64.AppImage and ffmpeg transcoding with h264_vulkan before that.