Hello once again,
I was wondering why do I have my HTML structure and classes changed on some pages (product detail on one site, and thank you page on every site) and discovered that it's a conflict between One Page Checkout and JoomSEF.
It takes my menu <ul class="nav "> and makes it <ul class="menu">. I just couldn't get it, how is this even possible. See - the same website, just one is on a bugged page (product detail, on the right side) and one is on a homepage (which is alright; in the left picture).
So I digged deeper into it and found out that it changes not only the main menu on the pic above, but every menu and all list-based (ul) modules. See my breadcrumbs code (on the left it's correct, and bugged on the right side - ul is gone):
And both of these pages share the template, it's not a template bug. When I turn JoomSEF off, it works. When I keep JoomSEF on and turn OnePage off, it works as well.
I also tried renaming all possible files and found out that this bug disappears when I rename \components\com_onepage\helpers\language.php to some nonsense (but of course, the onepage checkout in the cart doesn't work then), so it could be some little creepy bug connected with this.
Do you have an idea how to make it work again? I'm using the latest com_onepage2.0.244 and the same goes for JoomSEF (latest, 4.5.1 I guess and its VM plugin 3.0.22).
Thank you for your support.