Followed your suggestions and burned the .iso to my disc. It played in the computer, but only after I went to the iso on the disc in file explorer and opened it with VLC, whereas my friend’s disc plays automatically. However, just putting the two discs in my Blu-Ray player came up with an interesting result; his disc was unreadable (simply called “Unknown”, where my disc was read as a data DVD that had no playable files.

I made sure to select “Mastered DVD” rather than “Like a USB flash drive” when burning, so I don’t know what’s going on there.