Testing units with flexdashboard

[glaf13]

Hi! I currently work on a Shiny dashboard using the flexdashboard package, where I have multiple tabs, written like this inside the .Rmd file, and that looks like this at the top:

Summary
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When I use the app, I am able to select the different tabs, "Summary" being the default one. However, when I start using the testing units, I am unable to select/switch between tabs. With a ShinyDriver$ command. I am only able to see the "Summary" one (it being the default one). Do you have an idea on how I could select another tab? Thanks in advance!