Is your container field located inside a portal?
"selecting in the Inspector the "Interactive Content" option and clicking over the correct field"
Try to revert the order:
1) click/select the correct field
2) select in the Inspector the "Interactive Content" option
Yes, PhilModJunk, the container is inside a portal.
raybaui, it doesn't work doing what you say. I already did it as explained in my original post.
PhilModJunk, thanks a lot. Your question gave me my answer. It works outside a portal.
Now, is there a way to make it work inside a portal?
No, and that's why I asked. The interactive optimization option does not work for container fields located inside the portal.
Thanks a lot PhilModJunk and raybaudi.