Nested folders not visible

[AC Question]

I'm using samsung S6 G920F and using app MY FILES (Default app) to explore files in phone. However, I could not see nested folders inside main folders. Ex. I'm having a folder name Document as primary. Inside that I've created folders such as PDF ,Excel etc. However, I can see only Document folder not PDF, Excel (nested folder). However, I could see all nested folder contents under primary folder Document. I would like to see nested folders. How to accomplish this.

Thanks