Yeah, I have the exact same question. I designed the same solution as you: in my intranet, I create a Table View of my feature class containing only the fields that I want to show, and therefore converting my feature class in a non spatial table. I upload my data to a Feature Service in AGOL without any warning. I can even see the table in my Feature Service in AGOL. So far, so good. But when I open the table, it is empty. No records. It has all the fields but no records.
Any hint would be appreciated.
p.s.: Using Pro 2.6. to define the Table View with data from an Enterprise Geodatabase.