@fordwaters said:

...changed some settings for read & write capabilities under the Sketchup application folder.
I doubt that will help at all...

SU doesn't write AutoSave's into the .app folder, by default unsaved models go into the 'AutoSave' folder...

Sketchup.find_support_files("","AutoSave")

which for me returns ["/Users/johns_iMac/Library/Application Support/SketchUp 2015/SketchUp/AutoSave/.DS_Store"] as mine is empty [by choice]...
Once you 'Save' or 'Save As' a file, it's new 'AutoSave' saves to the same folder as the new skp.
the one for 'Untitled' stays in the folder, but it is then a dead link, that won't open...

To clarify your issue...
1: You are 'AutoSaving' an 'Untitled' drawing
2: you then name by using 'Save' or 'Save As'?
3: after this manual save, you get the 'Failed to save file' error, at the pre-set time limit...

I can replicate this only if I Lock the folder after I first save it, or manually move it from my user folder...

but then I am unable to 'Save' without the same warning...

Are you running as 'root/admin'? as that's the only way I can see how you can get this issue...

as 'root' you can save to anywhere you like without 'error' messages, but SU can't write to the same scope as 'root' so 'AutoSave' would fail...

john