export with expand=1 fails with start= and end= parameters despite being required

[AMA3]

Baikal version: 0.10.1

Expected behaviour:
ICS calendar should be exported with events between start and end times.

Current behaviour:
With expand=1 but not start= or end=, Baikal says:

<d:error>
<s:sabredav-version>4.7.0</s:sabredav-version>
<s:exception>Sabre\DAV\Exception\BadRequest</s:exception>
<s:message>
If you'd like to expand recurrences, you must specify both a start= and end= parameter.
</s:message>
</d:error>

With expand=1 plus a start= and end= timestamp, Baikal says:

<d:error>
<s:sabredav-version>4.7.0</s:sabredav-version>
<s:exception>Sabre\VObject\ParseException</s:exception>
<s:message>
This parser only supports VCARD and VCALENDAR files
</s:message>
</d:error>

With start= and end= but not expand=1, Baikal says:

BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:-//SabreDAV//SabreDAV 4.7.0//EN
X-WR-CALNAME:Calendar Name
X-APPLE-CALENDAR-COLOR:#ff9800ff
END:VCALENDAR

Steps to reproduce:

1. Issue a request such as:
   https://SERVER/dav.php/calendars/USER/CAL/?export&expand=1
2. Issue a request such as:
   https://SERVER/dav.php/calendars/USER/CAL/?export&expand=1&start=1736485200&end=1736571599
3. Issue a request such as:
   https://SERVER/dav.php/calendars/USER/CAL/?export&start=1736485200&end=1736571599

I was previously using sabre/dav 4.4 without Baikal and the second option (with all of expand=1, start= and end= parameters) correctly returned the calendar's events between the start and end times.

[AMA3]

I went back and re-installed my old sabre/dav 4.4 calendar server accessing the same database, and it is giving me the same error for the second request. So I tried to do a little debugging, and this is what I found before getting lost.

1. The error is caused by an exception thrown on line 169 of vendor/sabre/vobject/lib/Parser/MimeDir.php.
2. The error is because the switch on line 161 encounters a timezone string (America/New_York) instead of an expected BEGIN:VCALENDAR or BEGIN:VCARD.
3. The call to $this->server->getProperties() on line 236 of vendor/sabre/dav/lib/CalDAV/ICSExportPlugin.php is, according to the comment that follows, supposed to return "a VCALENDAR with a single VTIMEZONE." However, it seems to just return the timezone string, not wrapped in a VCALENDAR.

I hope this helps someone in figuring out the problem! I couldn't trace through the code any farther to figure out where this property value is obtained from. If someone knows and can point me in the right direction, I might be able to debug further.