I am trying to create a doorway and found this guide on how to do it along with an interactive door (?v=7uzTL9cbwhs) however, no matter what I do and following the tutorial to the letter I am unable to reproduce what they had at 2:09 (a rectangular hole through the wall). Any ideas? Have things changed since the video in relation to this?
It should still work the same. How exactly does it look like in your case? 
Just add a bsp and another one which is subtractive + change the scale of it or deform it with the vertices (bsp edit mode)
It is invisible once put in subtractive mode and does not affect the other bsp box at all even though it is scaled to the same width etc and as I say, follows the tutorial basically to the letter.
Here is what I get no matter where in the other BSP box I put it. It (the subtractive box) is to the same thickness as the other BSP box.
The thing with the invisibility is always like that -> probably you have disabled “update bsp automatically”. Go to editor prefereneces - Miscellaneous
The thing is is that it is set to automatically update (I just went to go change it and found out)
I personally would recommend you to always make it a little bit larger than the additive bsp
did you see the image I attached to an earlier post? I made a mistake and posted it to the wrong one but it is there so that you can see it.
Also, it is 22 and the width of the additive bsp is 20 so it is larger.
So you still have the same problem? -> probably you could send me the map so that I can take a look at it? + what happens when you increase the size of your subtractive brush to 30-40? + create a new project and test it
well, i tried it in a new project and it worked. sad thing is that i had put a few hours into blueprints for that project (trying to figure them out) and came up with some useful ones. any way to easily transition them over (and yes, they are class blueprints, not level ones)?
Just copy and paste the entire content folder into your new project or use the migration tool
thank you. could you please check out this other thread of mine? Need a staff answer to it. Thanks in advance!
https://forums.unrealengine/showthread.php?76769-Patches-and-updates
I had a similar problem and came across this thread. I eventually did a little experiment. Instead of using the geometry that loads as a standard in a new level, a inserted geometry and then tried a subtract - worked perfectly. So all I can surmise is that the standard geometry that loads with a new level has some different characteristics.