Unable to waterlog doors 1.13 Minecraft
Solution 1:
This behaviour is officially considered a bug: https://bugs.mojang.com/browse/MC-125351
Doors are an especially bad case of this, since they generate with shipwrecks. 1.13 has a lot of pretty bad bugs, which is one of the reasons why I recommend staying on 1.12.2 at least until 1.14.0 is out.