Noticed a bug in 6.3.8 when trying to select different font weights for various screen sizes. It’s not possible to make a selection with the mouse - it can be done by using the up/down arrows on the keyboard however.
Same applies to the actual font choice as well.
I think this affects most select boxes in the query breakout. We will have a fix for this in the next release. Thanks for bringing this to me and have a great day!