So i've been having this problems and many people who have macs are having this problem too. So when I download the tray importer for mac it opens and closes immediately and I really want to use it... also its says that I need to use Mono so there's no link so I searched for it and download it but anyway it didn't work! Another thing there was an update in macs cold MacOs Sierra so I think is that plz help
Yeah, it's a known bug, for unknown reason the settings are not saved.
Here's a workaround:
Open Finder, then browse to your Documents folder.
Create a folder name "Sims 4 Tray Importer" w/o the quotes.
Download Sims4.GameInfos.Settings.zip and extract Sims4.GameInfos.Settings.xml in that folder.
Apply your settings then save the changes.
Restart S4TI if needed
See if it fix the problem