Wow, well I realized one fix is to call
this->HasValidItemsSource() to fix the identifier not found error.
Wow, in fact, all the properties are accessible with “this - >” Phew, I’m glad I found a fix that’s actually stupid simple. I take back what I said about this being a huge issue.
Something about how I’m accessing from a template class confuses the compiler now so it needs an explicit this-> in my modules.