I've never seen that.  Is it always Clerics?

Does the description mention they require essence? Or do they show up as greyed out with that reason in the build list?

In FE, where Clerics provided a bonus dependent on the amount of essence the city had, it made sense for them not to be available to cities without essence. In LH, where Clerics provide a flat bonus, it just feels like an arbitrary distinction which punishes not taking spots with essence.

I believe that Guardian Statues, Guardian Idols, and a few of the upgrades to Conclave buildings also require essence for construction since they required it in FE, but I'm not certain.

IIRC, Derek Paxton confirmed some weeks ago that this is working as designed (clerics and their upgrade - shrine/temple of essence still requiring essence). i guess that's another point where the game could be easily(?) improved with better descriptions/tooltips. if i had to name one thing for the next patch that absolutely should be done, it would be better descriptions for buildings/traits/(some) other game concepts (such as swarming for example)