Sorry for the delay!
The problem keeps coming back because the fixed header container has a very high Z-index to start with (10000).
So there are three elements to consider.
1. the sticky element
2. the sticky header container (Z-index:10000)
3. the black overlay when quick view is open (Z-index: 10000)
First, you’ll have to make sure that the black overlay has the highest Z-index of the three, so that it will overlap the other two.
Then, make sure that the sticky element (the one with the login menu) has a higher Z-index than the sticky header container, so that the login menu won’t be obscured.
Once you’ve set that properly (for example, change the value for the sticky header container to 9000 and then set the sticky element to 9500), things should be working good. It’s a matter of prioritizing, really — which elements should be on top of which other elements.
As you can see, this is a good example why setting high values for Z-indexes isn’t always a great idea. ?? There’s never really a good reason to go as high as 10000, myself I always try to keep things below 100.
Hope this helps!