R check error: no visible global function definition for a function that is defined within the package

Question

I am developing a package in R. When I run R checks, I get the following note:

"reefSteady: no visible global function definition for 'tuneUR'"

Both reefSteady() and tuneUR() are functions that are defined within the package.

tuneUR() is exported and included in the NAMESPACE file. All documentation is being automatically generated by roxygen2. I have tried manually editing the NAMESPACE file to move export(tuneUR) above export(reefSteady) I but still get the note. I am using RStudio.

Not sure how to make it pass checks. The repo is stored here.