The documents folder with the green check mark that shows up under this PC on my computer is the OneDrive folder, not the local one.
If the wording in my first post was confusing, I apologise but the situation you are in now is the same as the one I was in after the main Windows update.
I also had a documents folder with a green check mark on it that showed under This PC as my OneDrive folder. I think the reason for this is as I said in my first post, there may be a duplicate registry entry. This means that you need to delete the duplicate registry entry that is superfluous to your need.
Before you do anything, I suggest you read all of the posts in the first link that I put above and then you will see that you have a very similar situation to what I had. To shorten the process, I did this below but I still think you need to read all of the posts in my first link above to get a grasp of the situation.
This is what I had to do:
1. Go to this registry key location.
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders
2. This is what you should see. (take the usual registry precautions before editing
your registry). Right click the value shown above that is labelled with the number 1 and
select delete.
3. Close all applications down & restart the computer. (Windows Explorer
should not show a green tick on the Documents folder now).
4. If your local folders are on a different drive to that of drive C, the ‘Documents’ folder will
be empty because it is now on the C drive. To move it to the drive of your choice so that
it will open up showing all your documents in it; right click the ‘Documents’ folder in the
left-hand column of Windows Explorer under ‘This PC’ and select ‘Properties.’
5. Then select the Location tab and type or paste into the location window the drive of your
choice (example below)
D:\My Documents
Finally, click Apply then OK.
HB