Hello again.
Frustrated 
by the situation here and almost desperate 
, I tried to find an alternative workaround with SFTP suppport, since WebDav is not a real alternative for me for security reasons as well as regarding MS Office handling. 
I managed to install a workaround parallel to NetDrive and use this alternative until buggy Netdrive is repaired: WINSSHFS. 
As you can see, WINSSHFS displays all folders and files correctly (unfortunately unlike the current NetDrive version). 
But: 
I can’t really recommend my workaround for normal users. 
The installation of the open source tool is a pain in the a**, numerous frameworks have to be added until the software runs (MS Visual 2013 Runtime, Dokan library, several reboots, etc. - all not included in the distributal setup). 
In addition, spooky shadow drives are faded in (spooldrive), which disappear when unmounted. 
WINSSHFS is also not bug-free: 
so the unmount doesn’t always work, sometimes you have to help to terminate it with the task manager. 
And: there are also minor bugs in connection with MS Office via SFTP which have not been solved in the Open Source community for months: e.g. you can open an Office file by double-clicking from the SFTP drive and save a new file without problems, but it is not possible to create a new file in the drive with 0 bytes with right mouse button > “New” or to save and overwrite an existing file with the same name directly from Microsoft Office (error message because of alleged missing permissions). If you save it under a new name it will work again. If you use alternative software like Libre Office everything is fine any you can even overwrite a existing file. 
Typical MS Office issues. 
So this is all just a “semigood” work around. 
We need our Netdrive3 with propper SFTP service and general prompt support again or alternatively a documented and traceable way confirmed by the support to a working downgrade (best with a link to the actually tested and working binary version). 
It is not okay to use paying existing customers as involuntary beta testers. 