Hi,
I’ve been using Setchup for quite a while on Win 8 and 10, 64bit.
After migrating to Sketchup Make 64bit I’m experiencing the following problem:
Sketchup claims it has no write permission to my Sketchup-Directory that resides in C:\users\username\documents\Sketchup
I’m using Sketchup with an administrative user, and I’ve installed Sketchup additionalle with “runas admin” options and also started Sketchup with “runas admin” for the first time.
Funny enough Sketchup can save models in C:\users\username\
Any ideas how that can be resolved?
Thanks a lot for suggestions
TimTom
Navigate to the user “Documents” folder and right-click “SketchUp” and choose “Properties”.
In the dialog, switch to the “Security” tab:

Verify that the user’s permissions are all “Allow”.
You might also, go on up the folder path verifying full permissions.
Also, make sure that the “SketchUp” documents folder has not been set as a “system” folder.
For example, from the SketchUp Ruby Console, the “Documents” folder is not writable, I think because it is a special “system” folder:
docs = "C:/Users/Dan/Documents"
File::writable?(docs)
>> false
File::writable_real?(docs)
>> false
But when testing the manually created “SketchUp” sub-folder:
path = "C:/Users/Dan/Documents/SketchUp"
File::writable?(path)
>> true
File::writable_real?(path)
>> true
REF:
I am having the same issue with LayOut (using 2017 Pro version). I followed the steps in @DanRathbun’s reply but to no avail! My temporary solution has been to save as a different name, but as I am not the only one accessing these files, this is bound to lead to confusion. Also, it is now happening many times per day (but not every time that I save), and it is really annoying. My coworkers access these files through Google Drive, and they have not had the same issue (they have Macs).
Any help would be greatly appreciated 
This was an old post re SU2016.
Contact Pro Technical Support directly and open a support ticket:
https://help.sketchup.com/en/contact/technical-support