Why not isolated?

[Kursk1943]

I isolated Novaya Ladoga the turn before, but the hex doesn't seem to be isolated. The Soviets don't have any ports at Lake Ladoga, no air supply. Perhaps fortresses have stores for several weeks?
Any ideas? Maybe a bug?

[APrusty]

The hex you have "Isolated" is a port-hex. They can recive supply from the other ports on lake ladoga. The port NE named ..asstroy can still supply them.
There is also a depot in that hex, so you need to starve them out after cutting their portsupply.

You can either use naval interdiction on the sea, or ground attack against the port.

[Kursk1943]

Okay, didn't spot the port symbols there and at the other fortress to the north, thanks!