Vanishing Commanders

[calmon]

One of my MP games is in year 5 now.

I had 2 Naiads in a province casting Voice of Tiamat. Some turns ago the first naiad suddenly vanished without any message.

In the messages i got a "Philia cast Voice of Tiamat". Instead of a picture of the commander there was just nothing at the start of the message.
No more information. The commander was just disappeared.

The second Naiad cast 1 more turn and moved than for 2 turns. In the actual turn the commander is vanished too. No information nothing, just no naiad where it should be.

I'm not sure what happens. I've a big nation with several hundreds commanders and thousands of troops. I'm not sure the 2 naiads were the only commanders but on the first look they were.

Did anybody notice something equal? Maybe its up to conjured commanders, maybe up to naiads but anyway its weird.