There are a few sites I prefer to view in desktop mode all the time (reddit/Facebook) but I find that locking my phone or sometimes just changing apps causes the tab to go back into mobile view, however, the toggle still shows desktop and the only way to fix it is to open a new tab which is pretty annoying esp if your halfway through reading a thread or something.

Is this a known bug? Is there anyway to make all tabs open in desktop mode permanently?