Cannot create project in Dropbox sub-directory

OK, I am just getting started, but have ‘taken the course’ and rummaged through the forum. I seem to have a hybrid problem of file access from what I can glean from this info.

I want to store projects in a Dropbox sub-directory, and this seems to be recommended in the section on saving work to the cloud. However, I get a file access error if I try to create a project in a Dropbox sub-directory, telling me I don’t have permission to write to this location. I can save a project to the Dropbox root directory without problem, so I don’t see why this should be happening. I seem to be forced to not organize my work. Is this normal? I obviously have permission to write to Dropbox subdirectories, I have loads of them in constant use.