I spawned in a new world next to a village. I grabbed a cartographer table and assigned a villager to it. I leveled it up to the journeyman level (which is the level where they sell the map to trial chambers) but he would not sell one. I tried this again on a different villager and the same thing happened. They would still sell maps to ocean monuments and woodland mansions but not the trial chambers. So I went into spectator mode and flew underground to try and find one, which I eventually did. I then spawned a villager, made him a cartographer and got him to the journeyman level. He then was able to give me a map to a trial chamber. It appears that they can only sell you a map to a trial chamber that is already loaded in the world, which is very inconsistent with how the other maps work. This can cause issues by making players in older worlds struggle to find these chambers by having travel far away and hoping that one has loaded in when they are trading with a villager. Hope that this can be resolved.

To duplicate go to seed 404462913451575369, immediately locate a plains biome then teleport to it, when you teleport there should be a village right next to you. Use one of those villagers to test out what I'm talking about.