PropertyDrawer: GetPropertyHeight#

Property Drawers don't have a layout phase that causes them to expand to contain the drawn content.
UI Toolkit property drawers don't have this restriction, but the editor will only use a UI Toolkit drawer if the editor containing it is also UI Toolkit.

Resolution#

This occurs every time the Property Drawer is used#

Manually define the height by overriding the GetPropertyHeight function.

This only occurs for the first element of a collection#

This was a bug that has been fixed in later Unity versions, update Unity to the latest patch version to get the fix.

Editor: Fixed ReorderableList first element height when the element uses PropertyDrawer. (1409773)