Footer disappears when using tikzpicture with pause in beamer

I want to have a sort of animation with each child of a root node appearing on a click. It works well except that the footer appears only when all animations complete for a slide. Maybe some can help fix the minimum reproducible example code below or propose another solution. Thanks in advance.

documentclass{beamer}
mode<presentation>{usetheme{Madrid}}

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usepackage[style=verbose]{biblatex}
bibliography{biblio}
usepackage[utf8]{inputenc}
usepackage{tikz}
usetikzlibrary{shapes.geometric, arrows}
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tikzstyle{startstop} = [rectangle, rounded corners, minimum width=3cm, minimum height=1cm,text centered, draw=black, fill=red!30]
tikzstyle{io} = [trapezium, trapezium left angle=70, trapezium right angle=110, minimum width=3cm, minimum height=1cm, text centered, draw=black, fill=blue!30]
tikzstyle{process} = [rectangle, minimum width=3cm, minimum height=1cm, text centered, text width=3cm, draw=black, fill=orange!30]
tikzstyle{decision} = [diamond, minimum width=3cm, minimum height=1cm, text centered, draw=black, fill=green!30]
tikzstyle{arrow} = [thick,->,>=stealth]
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title[tikzpicture with beamer]{}

begin{document}
begin{frame}{tikzpicture}{}
begin{tikzpicture}[node distance=3cm]

node (root) [process] {root};
node (child1) [process, below of=root, xshift=-4cm] {child1};
draw [arrow] (root) -- (child1);

pause 
node (child2) [process, below of=root, xshift=0cm] {child2};
draw [arrow] (root) -- (child2);

pause 
node (child3) [process, below of=root, xshift=4cm] {child3};
draw [arrow] (root) -- (child3);

end{tikzpicture}   

end{frame}

end{document}