This might be intended/wanted behaviour. You can place the bucket while shifting. Much like how chests work, the water won't place itself on the chest unless you are shifting.
@Kay, I'm pretty sure this has nothing to do with any world file. The message outputs before Minecraft tries to load any file.
I think they should have fixed this by the end of this week. I'm seeing many reports. Certainly infuriating!
Confirmed for 1.16. Also, the scoreboard statistic and the menu statistic do not always match when igniting TNT.