Fraction bar is not visible in Makie plot with text! and annotations! methods

Hello,

I tried to insert an equation with the text! and annotations! methods in Makie. Unfortunately, the fraction bar is not visible for me. However, the fraction bar is visible in the Axis title, xlabel, ylabel and the legend title. The problem is also in the exported figures. I tried it with CairoMakie and GLMakie.

using CairoMakie

let 
    fig=Figure()
    ax1 = Axis(fig[1,1], 
        title=L"\frac{a}{b}", 
        xlabel=L"\frac{a}{b}",
        ylabel=L"\frac{a}{b}")
    text!(L"\frac{a}{b}")
    annotations!(L"\frac{a}{b}", position=(0.2,0.2))
    scatter!([0.5],[0.5], label="test")
    Legend(fig[1,2], ax1, L"\frac{a}{b}")
    save("test.png", fig)
    fig
end

My Makie versions are:
[13f3f980] CairoMakie v0.7.2
[e9467ef8] GLMakie v0.5.2

Many thanks for your help!