trying to make an invisible wall. Keep having this issue

[Dubbag]

I've been trying to make an invisible wall for my wad but cant figure out how to stop this problem. I've tried flipping sidedefs linedefs and everything .

[Nine Inch Heels]

Select the linedef where you need the wall to be, make sure it has no textures assigned at all (if you really want it to be invisible), and then give it the "impassable" flag. When that's done, the only things that can pass through are projectiles or hitscan attacks.

 

If want a wall that also blocks hitscans and projectiles, you need self referencing sectors (vanilla), or fake ceiling/floor heights (Boom, ZDoom, UDMF though UDMF probably has different flags that could get you there as well)

[Walter confetti]

I spotted a translucent lines usage in your screenshot, so i think this map could be for Boom?

anyway, yeah go ahead with using fake floor / ceiling (line 242 in the editor) in that sector, so the bug will disappear!

[Nevander]

Try disconnecting the sides where it joins with the outer wall, leave 1 unit between them. Then raise the floor up to the ceiling leaving 1 unit gap.