Hi,
I am unable to recruit Gundabad Stone Trolls if both my fortress and Troll Lair need to be rebuilt after I have purchased the Gundabad Upgrade. I have played around and this does not happen in the case of Horrors of Gram i.e. if I have to rebuild both the fortress and the Mountain-orc Lodge, I can still recruit two battalions of Horrors (as per the Gundabad upgrade). This bug seems to happen on all maps.
Regards
Joel
PS. AOTR rocks! So stoked a game series I have been playing for over 15 years is still being developed and improved!