I’ve tried the better part of the morning to get an custom migration for D8 up and running. I stumbled on the very first step. Migrate Plus doesn’t recognized my migration. After some hairpulling, I came across a blog post by Mike Ryan.
If in 8.0.x you were implementing migrations by providing .yml files in config/install, you’ll need to rename those files from migrate.migration.* to migrate_plus.migration.* (because it is now the contrib migrate_plus module rather than the core migrate module which implements migration configuration entities).
Simple naming issue – aaah, slapping myself, whosh -. Thats why I dislike fileNameMagic. With some explicit config …, well I guess, I would hunt another thing :S