When i bought my SP4 I had some problem. One was that i couldnt make a recovery drive.
The second problem was with Word 2016. I got an eror trying to save my dokuments. It had something to do with temporary files.
And some freezing of the screen.
I decided to do a full reinstallation.
Keep nothing. After the complete reinstallation all my problems disappeared.
I think some SP4 was shipped with a bad installation of Windows 10.
My recommendation is to download latest Win10 and install it fresh. Takes about 30 minutes.
For me it was the right thing to do. No more errors and it feels quicker.