Hi Kevin,
Joe is correct that a major improvement was made to Event Calendar Pro in that it now correctly adjusts automatically to daylight savings.
However, it does pose a problem for events that were entered before the new timezone handling was implemented and unfortunately the only way to fix it is to correct the dates on the affected events.
Dates entered from the UI as local time and adjusted to UTC and stored in the database and then adjusted back to local time in the UI, the problem is that the UTC times stored under the old system were incorrect if you created dates during standard time for dates that occur during daylight savings time. Previously we only had a hard coded offset whereas now we take into account the correct offset for each date and it is adjusted correctly for daylight savings.
So for example take Eastern Time Zone, it has a 5 hour offset during standard time and a 4 hour offset during daylight savings. In the old system the offset did not adjust so it was always using the hard coded 5 hour amount and this would make events you entered into the system during daylight savings incorrect unless you adjusted the offset manually during daylight savings. If you entered dates during standard time but the dates occurred during daylight savings, the 5 hour offset was used to calculate the UTC time to store in the database, whereas in the new system it would adjust correctly by 4 hours when calculating the utc to store in the database. The problem is that old events were entered with an incorrect 5 hour offset and now it is still adjusting them for display using the 4 hour daylight savings offset. So the only way to solve it is to correct it on the events and this will make it calculate the correct utc date.
Sorry, I know this can be a hassle if you have a lot of dates entered already, but it will be correct now going forward and you would have encountered other date adjustment problems during daylight savings under the old system.
Best,
Joe