Hi, as you know, it's a known bug... according to this link the fix will also be included in next 3.0 release (i suppose earlier than 3.1).
I've seen a work arround for angled one way surfaces in this video with ray cast. I think the same should work with platforms moving up. For platforms moving down, perhaps getfloorvelocity ( ) can help you update the velocity of your player (if it's a kinematicbody2d) so it does not float. If you can share the code, may be we can try some workarround.