I want to use quick backdrops because they are fast to use in 32x32 grid based game. However, I have countered issues where scaled active objects combined with quick backdrops have trouble detecting collisions. Usually 65-90 angle collision from below or from the top works fine, but south east/ south west angled collisions tend to fail. Messing with detection type (fine collision on/of) can make things work but it always seems finicky.
I mainly encounter this when I use (for the line of site) an active object that is stretched from a point to an active object, and then I do check if that line is overlapping backdrop. Quick backdrops are all 32x32 based. If I use quick backdrops (marked as obstacle) they tend to fail, however if I place normal backdrop instead, things work fine (unless I check collision with a box). What is going on here?