The bug
When a door (or 2-block plant) is placed so that the top half of it would be above the world build height, it refuses to be placed, but the usual message about the world build height being there is not shown. Placing one so that both halves would be above the limit shows the error as usual.
Linked issues
relates to 6
MC-184430
A structure block gives no warning when the structure would cut off outside the height limit
Open
MC-278815
Build limit warning shows when trying to place blocks which otherwise would not be placeable anyways
Resolved
MC-11211
Unable to perform many right click actions when targeting the top face of blocks placed at y=255
Resolved
MC-129886
Trying to place a block below the bottom of the world does not give an error message
Resolved
MC-184432
There is no warning when using bone meal on plants that try to grow above or below the world height limits
Resolved
1 more links
In 1.16, 1.16.1 and 20w27a