Heya team, I'm sure the answer is "not currently possible" but figured I'd ask anyway. In an ideal world Bluebeam would let you apply the document scale to the layout dimensions, so when you're changing the size of a markup or moving it to a particular position, it will be to the set scale, and not just the standard document scale. Easy enough to do manually in your head with easy drawing scales (1:100 etc) harder to do for other scales.
Affinity Designer has this feature and it works well, you can switch back and forth between the set scale and the document units.
There's not a setting I'm missing to turn this on? I've dug pretty hard already.