After you have checked all that you might want to check the paths of your R libraries with
.libPaths()
I found on my macOS system that R somehow uses two different library paths. My understanding is it first uses the path mentioned first, but this might lead to unwanted side effects. You could try consolidating the libraries (though I am no expert in that) or specifically mentioning which libray to use with the comand (eg.)
library(“h2o”, lib.loc = “/Users/m_lauber/Library/R/3.5/library/”)