Villagers not recognizing profession blocks in survival single player game

In a villager trading hall which traps the villagers on beds covered and surrounded by glass. Previously I've been able to place the profession blocks at the end of the beds which the villagers can pathfind to and use. For no apparent reason the profession blocks are no longer activating (no particle effect from the block or a villager). I cannot replicate this bug in a creative world where an identical trading hall works fine.