Awakening of Evil

I can't finish the second mission.
I've completed all the quests I could, the human leader gave me the last one – to kill the orcs, and I secured the support of the elves, but I can't attack the orcs. Also, no reinforcements appear on the way to the orcs (except for the emerald dragons that the elf gave me).
Is this a bug, or what? How can I fix it? I really don't want to spend another week replaying it.
Screenshots: https://clip2net.com/s/4iLPlve
https://clip2net.com/s/4iLPnRj