How to use touying's pause within a fletcher diagram with math mode

Questions
, ,
1

I’m trying to make animated diagrams in a touying presentation. Consider the following MWE:

#import "@preview/touying:0.6.1": *
#import "@preview/fletcher:0.5.7" as fletcher: node, edge
#import themes.university: *
#let diagram = touying-reducer.with(
    reduce: fletcher.diagram, cover: fletcher.hide
)
#show: university-theme
#slide[
    #diagram($A$, pause, node((1, 0), $B$))
]

this creates, as expected, two slides,
image

image
image256×104 1.15 KB

If we replace the call to $diagram$ with

#diagram($A$, pause, $&B$)

we get twice the same slide, both slides containing both A and B, as if pause didn’t hide B.

How can I use the convenient math-mode notation for diagrams and have animations?