I, too, am having this problem with a brand new install, on a new Windows 10 PC. Thunderbird 45.8.0 with built-in Lightning.
However, in checking in Lightning options, there was one called "Show reminders for past events" (or words like that). It was checked by default. So, I unchecked it.
I, too, am having this problem with a brand new install, on a new Windows 10 PC. Thunderbird 45.8.0 with built-in Lightning.
However, in checking in Lightning options, there was one called "Show reminders for past events" (or words like that). It was checked by default. So, I unchecked it.
No more reminders for past reoccurring event. :D