Interacting with a cauldron while holding an empty bucket does not fill the bucket. Also, interacting with a cauldron while holding a water bottle does not fill the cauldron. These are the expected results, as in a 1.12.2 single player world the interactions give these expected results.
Title: Some cauldron-item interactions missing
Glowstone build: c4c59a7ebd263cf220a88382e882073bca7d267d
Interacting with a cauldron while holding an empty bucket does not fill the bucket. Also, interacting with a cauldron while holding a water bottle does not fill the cauldron. These are the expected results, as in a 1.12.2 single player world the interactions give these expected results.