So I just recently picked up mapping for Team Fortress Classic again. I hadn't done it for a few years, so I was actually surprised how well everything worked with my new computer, operating system and all. Except one thing: The wad.txt would not be included properly, as seen below.
This happens when your wad.txt looks somewhat like this:
This actually has a very simple fix: Just add a backslash ( \ ) to the beginning of every line and it should work perfectly fine.