hey @Himanshu_Sehgal
Data methods are mostly unique to the app locations, not all app locations will have access to the ticket object, in the introduction section(Data Methods) you can find the list of methods available for the app locations.
To overcome this you can use multiple app locations, and send the data from the app location that has access to the ticket object to the cti_global_sidebar location, please refer to the instance method documentation to understand how to achieve this(Instance Method)
Hope this helps
Stay Safe 