gganimate doesn't correctly render text in expression()

[moondog1969]

Plotmath text with expression() is not working on axes in animations. For instance, the 2 is not super-scripted for the equation on the y-axis label in the plot below.

ggplot(mtcars, aes(mpg, disp)) +
geom_point(aes(color = gear)) +
transition_states(gear, transition_length = 2, state_length = 1) +
enter_fade() +
ylab(expression(E = mc^2)) +
exit_fade()

I'm using:
R version 4.4.2 (2024-10-31 ucrt)
Platform: x86_64-w64-mingw32/x64
Running under: Windows 10 x64 (build 17134)

Thanks