Plum compatible with Cherry rootstock?

I know plum is supposed to be incompatible with Cherry but many of my grafts to Cherry took and are growing atleast as well as on the plum tree next to it.

A few appear incompatible though: Flavor supreme and Luisa grafts have both died.

OTOH Santa Rosa and Flavor Queen are both growing vigorously. My Jubilee plum from last year is large enough to start bearing fruit.