iCal Export of User Calendar

When I open my user calendar in Thunderbird, it pulls in my Gantt chart. If the start time is June 6 and the end time on a project is June 18, it isn’t shown as a day-long activity. Instead, each project is a midnight-to-midnight “stripe” on the calendar, filling up each day so much that I can’t see what anything is.

When I open the iCal file and import a single project, it loads the “event” as an all-day-event and puts it at the top of the day’s view.

Any tips on fixing this? I want to see my current work in Thunderbird, but in a legible way. Thanks.