Fail to install RCall - Julia package

Question

Following RCall's documentation, I ran Pkg.add("RCall") which looked to be working. Then, running using RCall gave:

WARNING: could not import StatsModels.Formula into RCall
ERROR: LoadError: RCall not properly installed. Please run Pkg.build("RCall")
#... few lines later
ERROR: Failed to precompile RCall [6f49c342-dc21-5d91-9882-a32aef131414] to C:\Users\jke4\.julia\compiled\v1.1\RCall\8GFyb.ji.

That's why I ran Pkg.build("RCall"):

┌ Error: Error building `RCall`:
│ ERROR: LoadError: R cannot be found. Set the "R_HOME" environment variable to re-run Pkg.build("RCall").

I believe, accordingly to RCall's documentation that I have to do a custom installation, but why can't am I able to simply install by Pkg.add("RCall") like it's suppose to be done?

RCall.jl can simply be installed with

Pkg.add("RCall")

Note:

• Julia version is 1.1.0.
• using Conda does work.
• There is no R version installed in my Windows computer
• I do understand what is my error message and how I can deal with it. My question is why do I have it whereas I wasn't suppose to, quoting RCall's documentation:

RCall.jl will automatically install R for you using Conda if it doesn't detect that you have R 3.4.0 or later installed already.

Update

Alright, I've done what @Cameron Bieganek suggests: pkg> pin [email protected] And it seems to work for a moment. However, after doing ] up, accordingly with the issue I had in this question.

using RCall now gives:

ERROR: LoadError: RCall not properly installed. Please run Pkg.build("RCall")

and Pkg.build("RCall"):

┌ Error: Error building `RCall`:
│ ERROR: LoadError: IOError: stat: invalid argument (EINVAL)

This time I can't get what's the error.

GitHub

Please note that this question is also referenced on GitHub RCall.jl.