When I run ocpu_start_app("my_package") not all the functions are displayed and I cannot access those that are not listed, although they are under the my_package/R/ folder as the OpenCPU documentation states.
In my case, it seemed to be an issue with roxygen2. This package creates the documentation and the NAMESPACE file that OpenCPU uses. For some reason, roxygen2 wasn't executing automatically when I built my package from RStudio (Ubuntu 18.04). So I had to run manually roxygen2. You can do this in several ways:
From roxygen2 documentation:
roxygen2::roxygenise(), or
devtools::document(), if you’re using devtools, or
Ctrl + Shift + D, if you’re using RStudio.
After this, I just had to rebuild my project and relaunch the OpenCPU single server and all started working again.