Hello, @nagy.pavol
Thanks for your patience.
We have double-checked the Agora Conference performance with the New responsive Engine and have to notify you that it works properly.
However, due to the fact that the new responsive engine is still in Beta Mode, there are some difficulties in UI/UX settings, as in your case.
Bubble has confirmed that a new plugin editor engine is under development and has top priority. We will migrate all of our plugins to the New Responsive Engine as soon as we have a chance to have them work properly on it. Here is the announcement from Bubble: Plugin Editor & New Responsive Engine [beta]
Sorry for this inconvenience 
In case we can help with any plugin-related information, let us know.
Best regards,
Zeroqode Support Team