Problema con Select list item: Attempt to get item number 2 of a list of length 1

[ABG]

I added a Debug Screen to your app, to show the CSV version of your sheet.

It looks like you want to filter by Carnet (row ID or student ID?) in column 2.

This block is useless, because you provide no event to catch its result:

So you are filtering in this request

(which should be called btnEnter in English, not btnBack, which should be used to return to a previous Screen via a Close Screen block.)

and should get only one row, the unique row for that row ID (or student ID?)

But look what you are expecting in return:

You are looking at row 2 of returnData, which will have only one row.

Also, you are loading returned data into attributes like NumbersOnly and Multiline, which are true/false flags, instead of into .Text, which is always where the text data goes.