Menu scrolls down the page rather than remaining fixes

After upgrading to the latest version of Simplicity last week, and updating Joomla to 3.6.5, along with all extensions, the menu now scrolls down the page rather than remaining fixed.

When the page is at the top of the page, the html is:
<div id="gkMenuWrap" class="active" style="top: 0px;"><div class="gkPage" id="gkHeaderNav">

As I scroll down, the html changes:

Simplicity moving menu.png

<div id="gkMenuWrap" class="active" style="top: 100px;"><div class="gkPage" id="gkHeaderNav">

<div id="gkMenuWrap" class="active" style="top: 200px;"><div class="gkPage" id="gkHeaderNav">

and so forth, until the menus is so low that it cannot be seen in the borwser.

See attached screenshot.

Please advise how to fix.

Thanks!

Allan

I found a template setting for the menu that was set to Slide and Fade, after the update. I set this to "None", but now the menu flickers.

Allan

It appears that the reason the menu flickers is that the html with the element CSS is till changing as above, but the menu is forced to stay on top. So, the menu flickers because it is constantly jumping back up to the top.

Here is a screenshot.

Simpicity flickering menu.png

Could you please provide me with a URL to your website, either here or via PM (click the “Private Message” text underneath my avatar) so that I may analyze it? It is a lot easier for us to diagnose issues when we have a live site to examine.