Windows 7, Thunderbird 52.9.1 (32-bit), Lightning 5.4 I have been using Lighting with Thunderbired for several years and it has worked perfectly synched to a Google Calendar. When I add an event I set the reminder to 1 day. What has started happening very recently (update to 59.9.1?) is that when I open an event in Thunderbird , say just to check the details but not to do any changes, the Reminder value gets set back to No Reminder. If I then close the opened event I am prompted to Save, Cancel or Dont Save. So Thunderbird thinks I've made changes. I have to 'Dont Save' to preserve the Reminder Setting. If I look at the Calendar online using Google Calendar the Events are all set with the correct reminders so it is definitely TB that is at fault I have Thunderbird set up on two other devices: one of them is also 52.9.1 and that exhibits in the same way. However on the other device the verion of TB is 52.7.0 /lightning 5.4.7 (later version!!!!) and that version opens an event and shows the reminder as it should be and when I close the event it does not prompt me to Save. So it looks like this issue has started with 52.9.1 Has anyone else seen this issue?