Labels of arrows in a tikzcd diagram not showing in Beamer

I just made a diagram for a Beamer presentation, but the names of the arrows involved do not appear after compiling. Here’s a picture reflecting the situation.

Here’s some minimal working example (actually, I include all the packages are part of the document)

documentclass{beamer}

AtBeginSubsection[]
{
begin{frame}
    frametitle{Índice}
    tableofcontents[currentsection,currentsubsection]
end{frame}
}

usepackage[spanish, activeacute]{babel}
usepackage[utf8]{inputenc}
usepackage[T1]{fontenc}
usepackage[gen]{eurosym}
usepackage{amsmath,amssymb}
usepackage{ae,aecompl}
usepackage{graphicx}
usepackage{mathrsfs}
usepackage{hyperref}
usepackage{xcolor}
usepackage{tcolorbox}
usepackage{tikz-cd}
usepackage{bm}

begin{document}
begin{frame}[fragile]
El núcleo de $mu$ es la intersección de los núcleos de $mu'$ y $mu''$.pause Por la hipótesis de inducción, existe un entorno $Vsubset U$ en el que existe una sizigia $lambda'$ para $mu'$ y una sizigia $mu''circlambda'$.
    $$
    begin{tikzcd}
        _nmathscr O^rarrow[r,"lambda''"]&_nmathscr O^sarrow[drr,"mu''circlambda'"]arrow[r,"lambda'"]&_nmathscr O^parrow[dr,"mu''"]arrow[r,"mu'"]&_nmathscr O^{q-1}
        &&&_nmathscr O
    end{tikzcd}
    $$
pause
Es evidente que $lambda=lambda'circlambda'': _nmathscr O^rrightarrow _nmathscr O^p$ es la sizigia de $mu$ que buscamos, concluyéndose así la demostración.
end{frame}
end{document}

Thanks in advance for your answers.

documentclass{beamer}

AtBeginSubsection[]
{
begin{frame}
    frametitle{Índice}
    tableofcontents[currentsection,currentsubsection]
end{frame}
}
usepackage{tikz-cd}
usetikzlibrary{babel}
usepackage[spanish, activeacute]{babel}
usepackage[utf8]{inputenc}
usepackage[T1]{fontenc}
usepackage[gen]{eurosym}
usepackage{amsmath,amssymb}
usepackage{ae,aecompl}
usepackage{graphicx}
usepackage{mathrsfs}
usepackage{hyperref}
usepackage{xcolor}
usepackage{tcolorbox}

usepackage{bm}

begin{document}
begin{frame}[fragile]
El núcleo de $mu$ es la intersección de los núcleos de $mu'$ y $mu''$.pause Por la hipótesis de inducción, existe un entorno $Vsubset U$ en el que existe una sizigia $lambda'$ para $mu'$ y una sizigia $mu''circlambda'$.
    [
    begin{tikzcd}
       {}_nmathscr{O}^rarrow[r,"lambda''"]&{}_nmathscr{O}arrow[drr,"mu''circlambda'"]arrow[r,"lambda'"]&{}_nmathscr{O}^parrow[dr,"mu''"]arrow[r,"mu'"]&{}_nmathscr{O}^{q-1}
        &&&{}_nmathscr{O}
    end{tikzcd}
    ]
pause
Es evidente que $lambda=lambda'circlambda'': {}_nmathscr{O}^rrightarrow{}_nmathscr{O}^p$ es la sizigia de $mu$ que buscamos, concluyéndose así la demostración.
end{frame}
end{document}