manual sync of folders with new files

Hopefully the below is not a duplicate. I searched the old issues, finding many variations on the theme, but none particular to my recent experience.

I have encountered abundant discussion in the context of the Android client on automatic synchronization, auto upload, two-way synchronization, and the like, and have become aware of the technical limitations in Android devices that inform these issues.

Recently, I noticed that if I synchronize a folder to the mobile device from the server, and then add a file to the folder, and finally, synchronize the folder again, the Android client ignores the new file. Discovery of the new file at the time of manually invoking the sync operation on the folder would appear not to be excluded by the same technical limitations that affect related synchronization concerns, and I find myself surprised that this case is not handled as I expected, which is to show the new file in the Android app's view of the folder and to upload the file to the server when the sync operation affecting the folder is requested.

Has this case been considered, and is the current behavior a deliberate choice, or possibly a design of omission?