IsLastBar is not set for indicators that are part of a cBot

I have a couple of custom indicators that render chart objects perfectly when used as standalone indicators. I use the IsLastBar property to only perform logic on realtime bars.

When I add the indicators to a cBot, the IsLastBar property is always false and the code block that relies on it is never hit.

For now I have worked around the problem by changing my logic to:

Bars.Count -1 == index  

Can you confirm if this is a bug or is the behaviour different to what im expecting when used with cbots?

Thanks