Folders/files are grayed out for non-manager members

When logged into my private groupsite as a non-manager member, I am experiencing an odd thing - in the file cabinet, files and folders which should be visible and available for me to download are instead grayed out.

I have viewed many posts and How-To videos regarding folder/file permissions, but have been unable to locate anything discussing folders/files being grayed out to non-manager groupsite members. 

It's crucial that non-manager members, in our private groupsite, be able to access the file cabinet, view folders/files and freely download them, but not upload or delete any of them (assuming permissions are set accordingly)  If I've got a setting wrong, could someone please tell me the right combination of permissions is to get the functionality we require?

I have done much trial and error, including applying each of the drop-down items under Manager > Group Settings > Basic Permission Control > Files & Media Permissions ("Default - follows group visibility", "Only may download", "Anyone may download") in order to test the results for a non-manager member - they all give the same results for non-manager members.

The folders are all set to:  "Default - follows file cabinet visibility" - no folders are set to "viewable by managers only" or "non-members can download".

When logged in as a manager (click on "File Cabinet" under "SHARE" tab) I can view and drill into the various levels of folders and subfolders, downloading all files - everything is visible and can be downloaded.

Then, I log out as a manger, log back in as a normal user (non-manager) and  click on "File Cabinet" under "SHARE". At first glance it appears all is fine, since I can see the top level list of folders just fine.  If, however, I click on a folder name or I expand a folder and click on a sub-folder, suddenly all the folders and files are grayed out - just barely visible. 

And to further confuse the issue, if as a non-manager member I click the "more" link at the bottom of a files module, the file cabinet page loads, showing the correct folder and its files - they are clearly visible and can be downloaded.  If, however, I attempt to click on any other folder, it suddenly becomes nearly invisible again.  Seems odd that I can see files only if I access them by clicking "more" from a files module (and that I can ONLY view those files and no others).

Is there a trick with the permissions either at the manage or folder level that I'm perhaps overlooking?  

Additional Note:  I see a ".locked-form" class is being applied to the folders/files section that is setting the opacity.  What does "locked-form" imply? 

Also - If as a non-manager member I click on the "plus" sign to expand a folder, then click on a subfolder, everything goes gray AND I can no longer click on any other Folder name or "plus" sign... I seem to be trapped at that level unless I reload the page.