It seems that both Regnitz Cathedral and Elzbach Palace are unable to use Emergency Repair, because it does not think they are within influence of a Town Center. The following are screenshots of a game where Elzbach Palace is within Town Center influence, has an icon on it that says it is receiving Town Center influence, is damaged enough to be able to use it, but has a red message saying “Requirement: In Influence” preventing it from being used.
Also noticed the same issue in my HRE games.
They are already aware of it, and fix is in progress. This was reported 20 day ago.