Solved! I posted this elsewhere but perhaps I could repeat it:
I had a dependency problem for MONTHS and couldn’t update my Shiny app.
I just worked around it by loading the dependencies accessing R in the terminal. From there, Rstudio found them. In your case, you’d have to open terminal, type R, and run install.packages(“tidyr”), then you should be able to go back into Rstudio and access it there.
This is a significant flaw in the IDE.