When certain mobs walk onto waterlogged bottom slabs, they will just stand there and never move. In the case of villagers, even if there is a zombie nearby, they won't run away.
HOW TO REPLICATE:
1.) Lure a mob onto a waterlogged bottom slab.
2.) Wait... it won't leave that block unless pushed out.
Thank you for your report!
However, we are already tracking this issue, and this report is a Duplicate of MC-157645, which is a report that has not been resolved yet.
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