Menu don't see on mobile device

@FvD

If you are upgrading theme with Drupal older version to newer version then it may issue of style conflict and style classes naming differences.

Need more information for replicate issue.

@FvD
Make Sure that you are not hiding menu for mobile from TB Mega menu configuration as attached screenshot.

@RaviKant

Thank you, view month ago, I changed the theme to https://www.drupal.org/project/bootstrap_barrio →

The subtheme I tried now, make the menue right!

@FvD
You can close the ticket if the issue is solved or Not need for more support.