System.tag.query missing custom properties

It seems that the function system.tag.query is not able to retrieve the information on custom properties.
Is this intentional?

We use this function a lot to sync our tags with external applications.
Would it be possible to add this to the existing functionality?

@SamDonche, while custom properties don't automatically populate in the UI (as there isn't a way for the system to get this information without an intensive query of the system), you can explicitly define them to be returned and you can search for values within a custom property. The dropdown fields allow you to manually type any value you would like and it will be used by the tool. system.tag.query also allows you to define custom fields within it as well.