Responsive Resize: Fix to Left/Top/Right/Bottom should be FIXED, not "Fixed until opposing side touches element then it's Fixed to that."
Currently, when you select turn on "Responsive Resize", then "Manual", selecting "Fixed to [Direction]" the element is only fixed to that direction until the opposing direction touches the element, for which the element is now pushed by that opposing direction and no longer Fixed to the Original Direction you set initially.
Current behavior: If element is 100-pixels from the left and it is fixed to the left, dragging the artboard from right-to-left will keep the element locked to left UNTIL the right edge touches the element and pushes it out of the left of the artboard. Overriding the "Fixed to Left" parameter that was set.
Expected behavior: If the element is 100-pixels from the left and it is fixed to that, it should always be 100-pixels from the left, even if the right outer bounds of the artboard is pushed up against it. It should cut off on the right edge of the artboard and not the left since the left was initially locked to that.
Thanks for the suggestion and the detailed explanation. We're actively refining the responsive resize behavior and will take this into account for a future update.