IIRC, there were some Python issues with the latest macOS Sigil build. As a workaround try the following:
- Select Edit > Preferences > Preferences Location
- Locate plugin.py in the plugins/DOCXImport folder and open it with a text editor.
- Change line #59 from:
Code:
supports_pyqt = (bk.launcher_version() >= 20170115)
to
Code:
supports_pyqt = (bk.launcher_version() >= 30170115)
This'll disable PyQt and should temporarily fix your problem. Note that the plugin might display a Python rocket icon in the dock that you might have to click to display the file selection dialog box.