I’d tried to import an online file as a compiling template typing the URL directly on the file dialogue. Everything froze.
By the way, the dialogue title is wrong. It shows “Export Compile Format” although you go to Compile/Import Formats.
Importing an URL via a file navigation dialog is definitely something you should not do. This is a Windows dialog and Scrivener has no control over it. Save the file to you hard drive via a browser and import the file instead.
The “Export Compile Format” title is obviously wrong and has been fixed in the next release.