A bit off topic but I am using Perl to generate the data and Template to format it...

I have a calendar that is synchronised with a a few people's Google Calendar, mine included. The Perl script generates an ICS file showing all the entries. Generally, they don't change date but they do change content. They are slots which customers can book and the VEVENT in the ICS file needs to change SUMMARY from 'vacant' to show the person's name, and a LOCATION tag gets added.

Google pulls the data in without issue when new slots are added. However, it will not update them. It won't change the time of the slot or show the person's name or location.

I have checked the ICS file against the ICS Validator and it passes fine. I've also added logging to my script to check that Google is actually reading the file - it reads it twice each day.

Here is my ICS showing just two entries - in the actual file there are around 25 entries

BEGIN:VCALENDAR
PRODID:-//EC Local Slot Calendar//EN
VERSION:2.0
CALSCALE:GREGORIAN
X-WR-CALNAME:EC Local Slot Calendar
X-WR-TIMEZONE:Europe/London
METHOD:PUBLISH
BEGIN:VEVENT
DTSTAMP:20230122T120000
DTSTART:20230122T120000
DTEND:20230122T133500
UID:EC27@businessgrowthcoventry.uk
SUMMARY:EC90 - Ian Boddison
DESCRIPTION:https://www.biz-cov.uk/admin#idEC27
LOCATION:Some test place
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20230125T120000
DTSTART:20230125T120000
DTEND:20230125T133000
UID:EC28@businessgrowthcoventry.uk
SUMMARY:EC90 - vacant
DESCRIPTION:https://www.biz-cov.uk/admin#idEC28
END:VEVENT
END:VCALENDAR
[download]

Can you suggest anything I can try to get this to update? It is rather difficult to debug as Google only pulls the data twice a day and it does it at unpredictable times!

UPDATE

Updated title to be more descriptive