BUG? "play all files in folder" switch doesn't work

[strawman]

using free version in samsung j3. I cannot play more than one audio file at a time. After playing the first file in a folder, I get kicked back to the home page and have to select "source" (SD card) and drill down to the folder I had opened before, to select the next file.
How to play more than one file or entire folder? I already went to preferences and selected a switch to "play all files in folder", but it does not work. Is this a bug?