Unable to add new property programatically using service AddPropertyDefinition in Thingworx

Hello,

I need to add couple of new properties to my Things at run-time. To achieve this I have tried using "AddPropertyDefinition" service from my composer environment. I am using ThingWorx 8.1.0. I sought references from various topics like - 

https://www.ptc.com/en/support/article?n=CS233812

https://support.ptc.com/help/thingworx_hc/thingworx_8_hc/index.html#page/ThingWorx/Help/Composer/Things/ThingProperties/ProgrammaticallyAddingPropertiestoThings.html

https://community.ptc.com/t5/ThingWorx-Developers/Thing-addProperty-doesn-t-work/m-p/527530#M21446

As mentioned in one of the links that it is needed to restart the Thing, I tried doing that, but doesn't work for me.

The execution of this service does not return any error, but does not give the expected output as well.

I tried to also use this service using "Test Service" button against the same service listed under generic services for a Thing.

Any possible reasons for the same?

Regards

Aditya Mittal