Convert Annotations to Grease Pencil There is obviously an answer to the question of converting GPencil from 2.79 to 2.8 here. Convert old GP to new GP

And this works but only if you open a 2.79 file with Gpencil in it. The Gpencil shows as annotations and you can use the same datablock on a Gpencil object.

However if you create an annotation inside of 2.8 you can't use the same datablock for the Gpencil.

I don't know if this is a bug or intended but it sucks :-)

Does anybody know of this issue and can help me report it to a dev? Or is there a solution?
Press F3 , then convert grease pencil