www.wysiwygwebbuilder.com

The submenu's in the CSS menu do not show when you mover the mouse over them.
Only the top-level menu is shown. You can see the sample on www.genders.nl.
I upgraded to version 18 but the menu still does not work. (tested with Chorme and Edge)

You have added several events and custom code, so it is difficult to make any sense from this based on the HTML code only.

To be able to help you, I need a DEMO project (.wbs file) so I can see all your settings.

I do not need the complete project because that will only take more time to figure out what you have done.
Basically, I just need a small project with one page and object(s) that are relevant to your question.

Note that I cannot see what you have done based on the published page (HTML), because the software has thousands of options and millions of possible combinations.
So, there is no way to know which options you have used by looking at the HTML only.

For further details about how to share a project file, please see this FAQ:
viewtopic.php?f=10&t=82134

If you click on the SUPPORT menu you will also see a CSS menu. This menu also has a submenus that do not appear. There is no code behind this sample menu.

I'm sorry, but it's not possible to see what you have done based on the HTML code.
There may be a conflict with other objects on the page or with custom code that you have added.
For example, the layer at the top may be monitoring the same events.

To be able to help you, I need a DEMO project (.wbs file) so I can see all your settings.

I have stripped our complete website and only left the CSS menu. Sample at www.genders.nl

How can i send you a copy of the wbs-file. I cannot find where to attach a file...

I think the issues is related to timing.
Can you please set the transition direction of the sub menu to '0' to see if that works for you?

I changed the following settings for the Main Menu and the Sub Menu
- Transition Duration for to 0 (Zero)
- Transion Timing to linear <= setting it to 0 is not possible.
- Transtion to none

The submenu still does not work

It works for me with your demo project.
Maybe you need to clear your browser cache?

Here's is your demo page, does this work for you?
https://wysiwygwebbuilder.com/support/genders/index.html