Summary:
Content is visible in a location in SharePoint Online, but the same location in the mapped drive is either empty, or some files are missing.
Cause:
There are two circumstances whereby a folder can appear either all, or partially empty, even though content is visible in SharePoint online.
1 - There are more than 5000 objects in that location in SP online. For example if you have 6000 word docs in a location such as:
https://tenancyname.sharepoint.com/sites/sitename/shared%20documents/Folder1
Then Folder1 would appear empty:
If 4999 of those word docs are placed in:
https://tenancyname.sharepoint.com/sites/sitename/shared%20documents/Folder1/Folder2
Then Folder1 would show the content again, as Folder1 has 5000 or less objects in it.
2 - The file path length limit is exceeded. There is a 256 character length limit included the tenancy, location and file names.
The tenancy name will be made up of - https://tenancyname.sharepoint.com@SSL\DavWWWRoot - however in a browser you won't see @SSL\DavWWWRoot.
This tends to happen when deep folder structures are used. For example:
Has 3 files in it named:
File1
File2
File3 - long - name - extra characters - extra characters - extra characters - extra characters - extra characters - extra characters - extra characters - extra characters
The total length of:
+
File3 - long - name - extra characters - extra characters - extra characters - extra characters - extra characters - extra characters - extra characters - extra characters
+ @SSL\DavWWWRoot
= 330 with spaces. A point to note, spaces count as three characters, so if they can be minimised in use or substituted for underscores, then this would cut down on the character length.
As the total length is 330, the folder will appear as empty:
If the long file name is renamed to File3, then it brings it down to 164 characters with spaces, content will be visible again then:
In the majority of cases like this, the whole folder will appear empty, however in some cases either just the long file name(S), or some of the other files won't show.
The only solution is to shorten long file names down, cut down on spaces and / or condense the folder structure.
Please note that one long file name can cause the whole folder to appear empty, or it can cause other files to not show.
If you require any further clarification on this then please contact support@iamcloud.com
Please note that this is a limitation with explorer. CDM (V3) will have a solution to handle longer file paths
V3 is not in production yet, but its at the pre release phase - https://www.iamcloud.com/iam-blog/news-cdm-v3-pre-release-update/ - if you'd like to try this, let us know and we'll have the setup details sent over.