Steps to reproduce:

I received an event invitation via e-mail.
The message shows Title, Location, When, Organizer, empty Description, and Attendees.

Looking at the raw data of the event, by looking at the actual source text of the attachment :
BEGIN:VCALENDAR
METHOD:REQUEST
PRODID:Microsoft Exchange Server 2010
VERSION:2.0
...

Right-click on the message body in Thunderbird -> Convert to -> event

Actual results:

A window pops up "New Event: {actual event title}"
Only two fields of the new event are brought in from the invitation: Title and "Related link" (mid:.....@domain.com )
The time and date are incorrect and set at the top of the next hour (from the current time).
Location is missing.

Expected results:

The fields should be filled with the information from the event invitation.

Here is the event in the raw format with the obfuscated private information:

BEGIN:VCALENDAR
METHOD:REQUEST
PRODID:Microsoft Exchange Server 2010
VERSION:2.0
BEGIN:VTIMEZONE
TZID:Eastern Standard Time
BEGIN:STANDARD
DTSTART:16010101T020000
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=1SU;BYMONTH=11
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:16010101T020000
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=2SU;BYMONTH=3
END:DAYLIGHT
END:VTIMEZONE
BEGIN:VEVENT
ORGANIZER;CN=First Last:MAILTO:first.last@domain.com
ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=NEEDS-ACTION;RSVP=TRUE;CN=Third Fourth:MAILTO:third.fourth@domain.com
DESCRIPTION;LANGUAGE=en-US:\n
UID:xxxxxxxxxxx[_Over80-chars-long_]xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
SUMMARY;LANGUAGE=en-US:My Event Title
DTSTART;TZID=Eastern Standard Time:20220406T140000
DTEND;TZID=Eastern Standard Time:20220406T150000
CLASS:PUBLIC
PRIORITY:5
DTSTAMP:20220330T185705Z
TRANSP:OPAQUE
STATUS:CONFIRMED
SEQUENCE:0
LOCATION;LANGUAGE=en-US:123 Main\, Suite 9876\, City NY 12345
X-MICROSOFT-CDO-APPT-SEQUENCE:0
X-MICROSOFT-CDO-OWNERAPPTID:-1136773146
X-MICROSOFT-CDO-BUSYSTATUS:TENTATIVE
X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY
X-MICROSOFT-CDO-ALLDAYEVENT:FALSE
X-MICROSOFT-CDO-IMPORTANCE:1
X-MICROSOFT-CDO-INSTTYPE:0
X-MICROSOFT-DONOTFORWARDMEETING:FALSE
X-MICROSOFT-DISALLOW-COUNTER:FALSE
BEGIN:VALARM
DESCRIPTION:REMINDER
TRIGGER;RELATED=START:-PT15M
ACTION:DISPLAY
END:VALARM
END:VEVENT
END:VCALENDAR

The two fields that do get filled in the new Calendar event are:

1. "Title" taken from "SUMMARY:" field:
   Title: My Event Title
   and
2. "Related Link:" taken from the Message-ID of the e-mail message with "mid:" added in front:
   Related Link: mid:12345678901234567890@domain.com

Additional information:
If I follow a different route for this event invitation: "Accept" -> "Do not send the response", the event does get filled with the correct information, except for what reported in Bug 1762304 (a set of different bugs related to the event posting via "accept").