Hi, Emma, thanks for your attention.
If I create a new course, there is no problem for this role to add any activity/resource. It only happen with the courses that we had before the upgrading of our LMS.
Anyway, finally I have tried to create a brand new role importing the permissions from the old one and to transfer the users with the old role into the new one and it looks it works. Finally, I have got rid of those permission denials.
Thanks again for your help, Emma.