No form validation control on 'required' if selectable in a form when option [selectObject] )=true

I am using Ionic 6.4.1. and Ionic-Selectable v4.9.0 (the last version that works with my app).
I noticed that when option [selectObject] )=false, the system detects properly that no item was selected and can show validation error message, but if i chose option [selectObject] )=true, it doesn't.
Any ideas why and how to fix it?