Prestige building favor at end of game?

[xdefect]

Hi,
I recently played a game of Caylus here and was confused with how one of the favor interactions worked. The end of the game was initiated by the last section of the Tower section in the castle being built. After this, royal favors were awarded. I received 3 favors because I had 6 houses in tower section of castle. For my first favor, I advanced on the building track to the final, Prestige Building, section. However I wasn't prompted to actually construct a prestige building. I had enough resources to build many of them, and also had two residences in place, but still was not prompted to build.

Am I missing an obvious rule here? If not, I'm not sure if this is a bug or if I somehow missed the prompt and just skipped past.

Thanks

[Miroku20X6]

Prestige buildings can only replace your own residential buildings. Perhaps you didn’t have any residential buildings on the board?

[Shivaware]

I looked through your game, and you definitely should have been able to build one of the prestige buildings at that point.

There is a bug report about it here: https://boardgamearena.com/bug?id=6625

The comment by volkerk is a possible explanation. When you select the buildings favor line, it's important to click on the correct building type. Is it possible that you clicked somewhere else to select the building row?