WorldServer return packages turn out always empty - how can I solve this?

Hi, I am using Trados Studio 2021 for Freelance. 

I constantly need to work on wsxz. packages for one of my clients. 

The workflow is:


1. The client sends me  wsxz. packages

2. I open it on Trados 2021 and translate

3. I create return packages  in the wsxz. format again and deliver it to the client (*I always do this from Project view)


Then, on step 3 there is always a problem; I can never create a proper wsxz. return package. I can create a wsxz. return package file, but it is always "empty" (the client's word) having only 22 bytes or so.

Could anybody please help me solve this problem? Any help would be very much appreciated.

Thank you in advance!