Element keys set with Reacton `.key(...)` are not recognized by the ipyvuetify transition group

Hello!
I'm not sure if this issue should be opened in reacton or ipyvuetify repository.
When I try to use Vuetify transition groups, I get an error in browser console saying:
[Vue warn]: <transition-group> children must be keyed: <v-dialog>

However I used a key method on reacton elements inside the group:

with rv.FadeTransition(group=True):
    if figures.raw_measurements:
        MplFigure(*figures.raw_measurements).key("raw_measurements")
    if figures.field_accuracy:
        MplFigure(*figures.field_accuracy).key("field_accuracy")
    if figures.calibration_moment:
        MplFigure(*figures.calibration_moment).key("calibration_moment")

(MplFigure here is a @reacton.component with rv.Dialog as the root element.)
Should the same keys be used by Vue in browser?

Reproduce the warning with rv.FadeTransition(group=True) and keyed MplFigure components, using rv.Dialog as the root element. Start by tracing how Reacton’s .key(...) is passed to the ipyvuetify transition group; done when Vue recognizes the keys and no longer reports unkeyed transition-group children.