Someone must have feed the bug, it's getting bigger.
Today: two friends are online, for both the other is not seen as online on the FL.
Adam sends an IM to Bertha. Bertha shows still as offline and does not receive the message.
Now Bertha messages to Adam, who appears as online then. He gets the message. His reply is still not visible for Bertha.
Mutual communication was only possible after both were standing next to each other on the same sim and he addresses her via the cake menu.