When a survey is available in more than 1 language, we have noticed that the dropdown menu that allows users to switch languages may become hidden from the viewport (depending on the width (pixels) of the browser screen/device), WHEN the 'width' URL parameter is used (and probably, only with some values of this param.).
The screenshots below correspond to a URL param. like "width=1920", as seen in viewports (aprox.) 680, 750, 820, and 1050 px wide, with a survey in English and French. You can see how, as the window's width increases, the dropdown menu becomes more and more out of the page:
device width=680
device width=750
device width=820
device width=1050