Rafael, does this issue persist on our Demo?
What the Software version are you using?
Did you try to reproduce this issue using default theme?
Have you performed the software or plugins/themes update recently?
Do you use third-party plugins?
Did you try to deactivate all third-party plugins to exclude them?
Did you enable the DEBUG_MODE to see if there are any PHP errors:
https://docs.oxwall.org/plugin-tuts:enable-debug ?
Did you try to enable FireBug console to see if there is any JS errors:
https://docs.oxwall.org/faq:parse-error-troubleshooting ?
Did you make any any code modifications ?