I've been playing ToE with the wonderful All Campaigns mod over the past week and I've run into what looks like a huge scripting bug in the final mission of vanilla HoMM 5's Necropolis campaign ("The Lord of Heresh").
After I retrieve Fredya from prison near Newpost (Haven town), I can safely transport her to Lorekeep (Necropolis town) with no events or enemy attacks - even though all the walkthroughs I looked up mention that I should be attacked by Angels sent by Godric in order to receive the Angel Wings artifact. This doesn't happen and once I reach Lorekeep, no other script is triggered. The "transport Fredya to Lorekeep" objective remains unchecked, the Angels don't spawn, I don't get the artifact and can't finish the mission.
Is there any way to fix this? Am I doing something wrong? Do I have to install vanilla HoMM5 and replay all the campaigns there?

FYI, I used Markal to retrieve Freyda, I let the Angels desert from Isabel's army on Day 2 (when the "desertion" script is activated), I haven't used any cheats, I'm playing the GOG version without the Advanced AI mod. I haven't tweaked any mod files and all the other mods I have (in-game Skillwheel - Doc Skills and Xazardous Skillwheel, Rage/Necro Button, tweaked Save/Load menu) should not clash with the scripting of the campaign. Aside from this stinker, I've only encountered one clear scripting error so far (the game wouldn't trigger the win state in single-player mission "Temptation").