Same problem here
I have a Windows XP file server with shared folders.
I have a RPi2 running LibreELEC
The Windows shares are added as video sources in Kodi on the RPi2.
On 8.0.2 the shares can be accessed fine.
After upgrading to 8.1.1, any attempt to access a share results in an "Operation not permitted"
I then downgraded back to 8.0.2 and everything continued to work as usual