I just lost a game because I was not able to repair my House of Wisdom (likely would have lost, but definitely still had a chance) .
Multiple times my villagers stopped repairing with “Insufficient stone”. Repairing the house of wisdom does not cost any stone.
It might have occurred because I was also repairing a keep with stone, although it happened multiple times upon clicking on the house of wisdom.
Only after buying stone, I was able to repair the House of Wisdom again (yet too late).
screenshot:
