How to clean rows based on a condition?

It's not possible to say why it doesn't work without seeing the data and the code used to process it.

However, you are in the best position to debug it (especially because you have a working sample to compare).

So, check the data types, write test columns to identify the issues, for example, you say all the rows were 'correct' so try editing the code to change the comparison to the opposite ('<' instead of '>', maybe) and see what that does and then investigate. 

And compare the 'real' data with the sample data. There must be something different.

edit:

Also there can sometimes be unusual results if the power query code folds back to the database.  I don't know what connection type is being used here to the Olist db but you can investigate that too (see query folding)