MMH5.5 - Heroes of Might and Magic 5.5

Good day! A player in a match discovered that when purchasing a 4th-level talisman for a hero, the city management skill disappears. It becomes impossible to rebuild the city or teleport to selected cities; you can only teleport to the nearest city thanks to the 4th-level talisman skill. This was, of course, his mistake when purchasing the 4th-level talisman, as it's possible that when purchasing a 3rd-level talisman (but we didn't know this yet), city management remains. Screenshots are attached. Is this a bug or not? We simply couldn't find a way to scroll through the hero's skills. Thanks if you can suggest a way to do this.
In the 1st screenshot, you can see the 1st-level talisman on the hero, and then the skill book of the leveled-up hero with the 4th talisman. We didn't find any buttons or another way to scroll through the skills.