Me again :-)

Bought the plugin and activated it but I still get the standard message from osclass. Can I change something so that the success message is shown?

Regards,
Marc

Try it without other plugins, multiple plugins may have conflict on same hook.

@MB Themes

Other plugins are deleted from folder so conflicting is not possible anymore.
Still no pop up when succes publish is added to site. Tried on mobile as on multiple browsers, cleared cache and welcome pop up works but no succes pop up.
Which hook is used and in what file please?
If you want i can give you credentials to look into this.
Regards,
Marc

@mwindey
You can send credentials, I will look into it.

Done