Nevermind. I found out the answer!
auto
Ha! I hate when people say they figured it out in forums without posting the solution. So here you go!
https://gbatemp.net/threads/io-seek.211071/#post-2628075
I went to the properties of the .iso file and unchecked "read only" and now it works!
I'm using WiiScrubber v1.4 and when I try to open up SSBBrawl I get an "io_seek" error. Some people say to just hold enter for a bit and ignore the errors and they goes away, but I've held down enter for 10 minutes with no indication that it's going to stop. After the first "io_seek" error...