With Windows 10 never combine the width of the taskbar items gets smaller and smaller as needed to fit everything in (desired behavior).

With Start11 never combine there seems to be a minimum item width and once that with has been reached Start11 simply doesn't show the items that don't fit on the taskbar. There is no indication that this is happening - just that you are looking for an item that has a window but isn't there on the taskbar.

I normally run my taskbar 2 or 3 rows high. I had to expand my taskbar to be 4 rows high just to be sure items don't disappear.