Error encountered while completing the final mission of the third campaign, "Tribes of the East".

So, here's the problem: when playing the last mission in the Orcs campaign ("Hunt the Hunter"), there's no way to attack the city of Shahibdiyah (they really come up with magical names, don't they), which needs to be captured according to the scenario. The entire map is open, all other cities have been captured, but when trying to attack Shahibdiyah (a powerful mage is stationed in the city), the hero simply stands at the city gates, and the attack doesn't happen. If the hero is left there at the end of the turn, the computer tries to move its second hero (to the gates), they end up on the same tile, and the game crashes. This is frustrating because, overall, I like the game, but I can't progress in the campaign.

The disc is a licensed copy, but it's a translated version. When I install the game on another computer and copy the save files over, the same thing happens. Can you please advise if there's any way to fix this? As far as I understand from the website's materials, there are no patches for "Lords of Might and Magic" yet...

Also, another question: if I buy the English version and load these save files into it, will that help? Will they even work?