If I Import and Split… in a project file, it works fine:

However, if I need to do it again and the project file has been open since the last time I did it, I get a messed-up dialog box:

If I close the project and re-open I can re-import again.
Scrivener 3.0.3
MacOS 10.14
Thanks, I’ve tracked the bug and have it fixed for 3.1, which shouldn’t be too much longer.