Same problem with me too!
i have tried all of the above, still no solution. I even ticket WD for this, but no reply 8 day now.
Make sure you don’t have any software (backup software, sync software, anything that might access the share for scanning or file management purposes). I had the same behavior until I realized my sync software was keeping a live connection under the admin account, preventing me to use some other credentials to access the shares through Windows explorer.
