Silvermist not visible / targetable bug

[Kylan]

I've had this for awhile now after I let a Silvermist loose. I get my ship to flee, and then return to the system where the Silvermist was. There wont be one anywhere near, and suddenly my ship will start to be eaten and try to flee from an invisible Silvermist. If I have a combat fleet they cannot target as there is no icon / identifier for the threat.