Vector Objects don't persist when modifying through Properties.

[coaster3000]

Bug was introduced during the initial addition of vector manipulation to events and entities.

Vectors don't persist through properties due to bukkit api nature on vectors.
It creates a new vector on every method you use against it.

There are two approaches to this kind of issue. Create a custom handle to it. Or a transformer to a Mutable version of vector provided similarlly to how item stacks work.

Will see what method seems best for future.

Current workarounds are to set the vectors with a new vector object with the previous vector values read through properties.