When attempting to add a project to Creator Companion that stores SDK3, CyanEmu, & Udon# in a subdirectory the import fails with the following error:
2022-05-17 23:59:23.630 +01:00 [WRN] Project at D:\VRChat Worlds\<Redacted>\VRChat World - <Redacted> looks like the type Unknown, which cannot be added.
The packages are stored in a 3rd-party subdirectory.
If the packages are moved to the root of the assets folder migration completes successfully.