This is abandonware. I have used it off and on for years because I already own it, and it (mostly) functions, but has quite a few bugs and inconsistencies. You are better off paying the extra $5 to get Dungeondraft, a program that does everything this one can and more, with a team of real Devs who do bugfixing and the like.

I've decided 20 hours into my current project that after I'm done with the map I'm currently working on I will never be using this program again, and I'll just have to eat the sunk cost of paying for and learning to use this trash fire of a program.

The biggest issue for me is when the program decides that some of its basic features just won't work at all until you restart it. There's nothing quite like being in the middle of some detail work overlaying textures to make the floor tiles you're really looking for and suddenly not being able to place down any texture boxes at all.

You should also always double check to ensure that the program actually updated the file when you press 'save' because sometimes it just doesn't. It's not very frequent, but every once in awhile you'll go through the entire process of overwriting the file only to find that the file has inexplicably not been updated at all. Keep file explorer open and double check before closing the program.

OR JUST USE A PROGRAM THAT ISN'T ABANDONWARE.