DB2 template node - this.msg behaviour is not consisteent

Hi

I have below below

DB2 Button --> Function Node --> Sends message to DB2 Template Node.
One of the attributes on msg changes based on Button.
Not the problem - if the attribute is deleted msg - yet Template node sees as attribute defines.

Step 1 -

Send msg with msg.x = ABC
Template node gets it.
when i do alert(this.msg.x) in template node i see ABC

Step 2 -
delete msg.x or set msg.x = undefined.
Template node gets it.
when i do alert(this.msg.x) in template node i still see ABC

I am not clear how it works.

Cancelling this as it was development issue.