Hello @pamtbaau
Thanks a lot, I followed your instructions and it worked! 
I was checking for these “onpage_menu” concepts on the docs (to check for more that I can learn, like these) and found this similar issue (that you also solved!) which I had not seen before and that extends this topic even more: Menus & Modular pages leaving it here in case it can help someone else!
Thank you again @pamtbaau !!!