Yes, Timing & Reminders was checked in Tools -> Options -> Appearance.
In the meantime I managed to fix this strange issue by finding a task I remembered had a recurrence. Once I edited that task, I saw Timing & Reminder for all other tasks.
Good to know about `or you can right-click on the "Properties" pane header"`, might come in handy if they disappear again. I'll try toggling that setting.