Dead keys not enabled, can't set them via system settings

I've recently installed xubuntu 16.10 and the dead keys of my spanish keyboard are not working.

I've tried a couple of alternatives using dpkg-reconfigure keyboard-configuration and the system layout is set to layout: latam which is almost correct but dead keys are not working and I can't use the right tildes.

Using xfce's proper system configuration tool doesn't make any difference.

What else can I try?