I found that in some situations FileMaker 17 doesn't close properly.
With no file open is it impossible to close FileMaker application and I need to kill the app.
I found this situation when FileMaker is hanging.
Workaround: kill the FileMaker app.
macOS High Sierra 10.13.5
FileMaker Server 126.96.36.199
FileMaker Pro Advanced 188.8.131.52