Problem with percussion sounds with MuseScore 4.3.0

I've been using MuseScore more than 15 years now.
I often use the 3.6.2 version because "tradition".
I work MuseScore with Ubuntu Studio 22.04.4 LTS (64 bit Linux) and all the audio environment is working with Jack Audio Connection Kit.
Time ago, I wrote a "piece" to test the "Change Instrument" command om each staff; specially intended to change percussion sets.
The file was wrote with MuseScore 3.6.2 and the "GeneralUser GS 1.471.sf2" soundfont file.
The idea is to use the different "flavours" of percussion sounds we have inside the soundfont (Standard, Power, Jazz, etc.)
This file run 100% fine with MuseScore 3.6.2.
BUT... When I play it with MuseScore 4.3.0... I just get a mess of sounds nothing related with the expected original percussion instruments.
Of course I guess it is my fault because I missed something in the way.
So... Can somebody teach me about how to convert this file to the new MuseScore version, please? ???

Blessings and Greetings from Chile!!!
JUAN