OpenGL breaks some textures

Basically what the title said. OpenGL mode breaks some of the textures on some lindefs, even though they share the same texture as the other lindefs around it which are perfectly fine. Any ideas?

Software:


OpenGL:

Anybody's first question is going to be what port you're using, and what version of it.

Their second question will be when are you uploading a tangible map so the lines/sides/sector references can be inspected, as screenshots will not tell anybody these.

I'm using Skulltag and Zandronum, latest versions, both cause the same problem (I haven't been able to get the addon to run in zdoom/gzdoom, probably because of the skulltag features). I cut the areas out into a seperate wad and tested them in zdoom/gzdoom, same issue.

I didn't include the wad as I thought there would have been people who had a similar problem. My bad. Here's a sample wad:
http://www.mediafire.com/file/87ap7hbovh71750/Broken.wad

Notice too how in the second area, the translucent lines have been broken too.

Those lines are missing the vital double sided flag. This likely works in Zandro's software renderer by mistake, but renderers are supposed to start occluding at the absence of this flag, hence why in OpenGL it stops. Put that flag back on the lines and it'll work again.

Thank you! Works perfectly