I apologize in advance for not providing a demonstrative snippet, as I can't precisely reproduce the conditions that lead me to the following situation.
Consider the video below:

I have two ListIcons with exactly the same flags (#PB_ListIcon_GridLines|#PB_ListIcon_FullRowSelect|#PB_ListIcon_AlwaysShowSelection) and subject to the same item sorting procedures with callback.
In the 1st case, to go to a specific item, I can type several letters to refine the positioning in the list.
Here, I quickly type 'N' then 'B' and the selection line is positioned on 'NB'.
In the 2nd case, I do exactly the same thing, but the behavior is different. The selection line is positioned first on the first word beginning with 'N', then on the first word beginning with 'B', and not on the first word beginning with 'NB'.
I have no idea why this behavior is different. Could anyone give me a possible reason ?
Thanks for your help.

