Very good Juan_Antonio!
It works now with my android 10 mobile.
With old one (Android 8) it does not anymore out of the box. I have to change the path to the gif images to
/storage/emulated/0/AppInventor/assets/
Seems that my AppInventor 2 resides in the first plane of internal memory, not in the Android directory.
I will test how it works if the APP is compiled...
Thanks again for your help!
Regards