Sequoia 15.5 bug? Adding calendar .ics file gives Zulu time (I'm in U.S.)

[Jumpthesnark]

I just installed Sequoia 15.5 today on Mac Mini M2 Pro, up from 15.4.1.

All seems fine, but I made some appointments and when the organization I made an appointment with sent me an .ics file to add to my calendar, it added the appointment at Zulu time (Greenwich Mean Time). I am in California, as is the organization I made the appointment with.

• My machine's time is set correctly to PDT.
• Settings>General>Date & Time>set date and time automatically is turned on
• Settings>General>Date & Time>set time zone automatically using current location is turned on
• Settings>General>Date & Time>Time Zone: Pacific Daylight Time
• Settings>General>Date & Time>Closest city: Cupertino, CA
• Calendar>Settings>Advanced>Turn on time zone support is checked on
• Settings>General>Language & Region>Region is set to United States.

Soon after that, I made a second appointment, and that .ics file also added the appointment to my calendar in Zulu/Greenwich Mean Time.

I opened the .ics file in TextEdit and here's the info it contained. I have blurred non-essential information.

Anyone else experiencing calendar weirdness like this in 15.5? Thanks!

 

[FreakinEurekan]

DTSTAMP, DTSTART, DTEND all specify Zulu (GMT)

When I create a .ICS file,it shows several fields yours is missing.

BEGIN:VCALENDAR
CALSCALE:GREGORIAN
VERSION:2.0
X-WR-CALNAME:Locke
METHOD:PUBLISH
PRODID:-//Apple Inc.//macOS 15.5//EN
BEGIN:VTIMEZONE
TZID:America/Chicago
BEGIN:DAYLIGHT
TZOFFSETFROM:-0600
DTSTART:20070311T020000
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=2SU
TZNAME:CDT
TZOFFSETTO:-0500
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:-0500
DTSTART:20071104T020000
RRULE:FREQ=YEARLY;BYMONTH=11;BYDAY=1SU
TZNAME:CST
TZOFFSETTO:-0600
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
TRANSP:OPAQUE
DTEND;TZID=America/Chicago:20250527T160000

Since the ICS actually specifies Zulu, what I'd expect is that the appointment would be imported as an event scheduled in GMT time, but actually showing on the calendar in your local (PDT) time zone. For example 16:25z would show on the calendar at 9:25am PDT. Is that what's happening?

 

[Jumpthesnark]

Since the ICS actually specifies Zulu, what I'd expect is that the appointment would be imported as an event scheduled in GMT time, but actually showing on the calendar in your local (PDT) time zone. For example 16:25z would show on the calendar at 9:25am PDT. Is that what's happening?

Thanks, but no. If that were happening there would be no problem. The event stays in Zulu time (GMT) numerically but it changes the time zone to mine. So an appointment at 9:25AM PDT is set, the organization sends me a .ics file that (when opened in a text editor) shows 16:25 Zulu/GMT, I add it to my calendar and it at that point appears in my calendar at 16:25 PDT, or 4:25PM PDT. It's like it understands the numerical time but not the time zone.

 

[svenmany]

I don't see this behavior when I import.

If you would upload a text version, rather than a screenshot, of a sanitized ics file that duplicates the problem, I will try to upload it to my calendar to see if the problem happens to me.

 

[Le Big Mac]

I just accepted a calendar invite, which shows as GMT (Zulu) but lands at the correct time in my (EDT) calendar.

What program is the org using to generate the calendar item?

What if you add the ics entry to your calendar via iPhone/iPad/other device? Given @FreakinEurekan 's analysis, I suspect the ics file is incomplete and it's not providing "conversion" information to your time zone so all iCal sees is the start time, without a time zone.