All responses -> Download in text format -> OK
Your Responses View x -> Download in text format -> The tabs seem to show that we are in All Responses mode (not in Your Responses) -> select your options and click the Download button -> You do get (correctly) a data file with your own responses only (not the students' responses).
So it does work as expected, despite of the "display bug".
However this behavior is confusing and for a teacher being able to download as text their own responses only has very little interest, and should be disabled from the tabs.
Joseph