Can't get my app to count or write to a data table

Hi - I’ve struggled for four days with this and I seem no clearer to getting it to work. I’m trying to create a logical flow where the app looks up a data table, separates out items (Texts) by username (into 2 lists: created by the user and created by other users), then orders each in reverse chronological order before amalgamating them into a final list and then uploading these reordered rows into a new data table (Session Display Texts).

The end result should be a source I can use for the data viewer grid on another screen to show the users created items (most recent first) followed by everyone else’s (also most recent first).

After half a week of struggle I’m no closer to success. My problems:

  1. Although the app now recognises 15 rows in my data table (correct) it then separates them into 2 from the current user and 2 from all other users). What happened to the other 11??
  2. It doesn’t write anything to Session Display Texts so I can’t see if the final list (the variable Final TextList) has anything in it at all.
  3. Further I can’t even devise a debugger to check what, if anything, is being written into each variable.
  4. I’m pulling my hair out here. I can confirm that there’s nothing wrong with my data table (I think).
    Any help or advice gratefully received.

Here’s a screenshot (I can’t find an option to embed on the community):

Thanks all!

Gavin.