I eventually did get my PowerApp to work, pulling information from Epicor via REST however I found i was not able to create the custom connector in PowerApps that would get what i needed from Epicor. As mentioned above, it was always empty. I just could not figure out why.
What i did get to work however was to first create the request and examples using Postman. I then exported the collection out of Postman and there happens to be an option in the Microsoft PowerApp environment to import a Postman collection as a custom connector.
Bingo! that worked. But, even setting up my custom connector by hand copying everything i could see from what MS did by importing the Postman collection, i still couldn’t get it to work. no idea…
So, in the end, i started to do all my work in postman and then exported the collection out and into MS to get what i needed. PowerApp created.
So what did I learn from all of this? Yes, i can create a PowerApp to pull simple information from Epicor but … doing even the simplest thing seemed very problematic, buggy, and just mind boggling confusing. I took a different route and found creating my own custom app (as mentioned here:Epicor Rest Helper (Nuget) Updated (1.1.11)) to be much simpler.
I had such high hopes for PowerApps. 