The January 2019 update contains a bug affecting To-Do List views. If you try to group by two fields, Outlook will tell you there is nothing to display. Only the To-Do List and To-Do bar are affected by this bug.
- Group by one field and sort by the other field (not all fields support Sort)
- Rollback one build
First, turn off updates and create an appointment on your calendar to turn updates back on in about a month.
- Type cmd on the start menu, right click on the Command Prompt, choose Run as Administrator
- Copy and paste this line in the command prompt. This command takes you back to the Jan 14 2019 build.
"C:\Program Files\Common Files\microsoft shared\ClickToRun\officec2rclient.exe" /update user updatetoversion=16.0.11126.20266
If you want to go back to an earlier build, the full list of build numbers are here Release notes for Monthly Channel releases in 2019