report by email sends email but no report

[dalers]

I sent a time report by email and received an empty email.

Report sent following: Reports > [enter report params] > Generate > [view displayed report] > Send by e-mail > [enter email params] > Send > ["Report Sent" shown]

Time Tracker is hosted using Apache 2.4 with PHP 8.1 and MariaDb 10.6

Mail is sent using php mail() per WEB-INF/config.php

// MAIL_MODE - mail sending mode. Can be 'mail' or 'smtp'.
// 'mail' - sending through php mail() function.
define('MAIL_MODE', 'mail');

Setting DEBUG to true in WEB-INF/config.php has no effect (no debug displayed)

// define('DEBUG', false); // Note: enabling DEBUG breaks redirects as debug output is printed before setting redirect header. define('DEBUG', true);

The Apache httpd-error.log has warnings but no errors:

[Mon Dec 16 09:28:40.872503 2024] [php:warn] [pid 60674] [client 162.223.103.50:56217] PHP Warning:  Array to string conversion in /usr/local/www/timetracker/WEB-INF/lib/form/Submit.class.php on line 44, referer: https://timetracker.dalescott.net/reports.php
[Mon Dec 16 09:29:45.108522 2024] [php:warn] [pid 61378] [client 162.223.103.50:33503] PHP Warning:  Undefined variable $print_subtotals in /usr/local/www/timetracker/WEB-INF/lib/ttReportHelper.class.php on line 1422, referer: https://timetracker.dalescott.net/report_send.php
[Mon Dec 16 09:29:45.108565 2024] [php:warn] [pid 61378] [client 162.223.103.50:33503] PHP Warning:  Undefined variable $print_subtotals in /usr/local/www/timetracker/WEB-INF/lib/ttReportHelper.class.php on line 1556, referer: https://timetracker.dalescott.net/report_send.php
[Mon Dec 16 09:29:45.108582 2024] [php:warn] [pid 61378] [client 162.223.103.50:33503] PHP Warning:  Undefined variable $print_subtotals in /usr/local/www/timetracker/WEB-INF/lib/ttReportHelper.class.php on line 1422, referer: https://timetracker.dalescott.net/report_send.php
[Mon Dec 16 09:29:45.108619 2024] [php:warn] [pid 61378] [client 162.223.103.50:33503] PHP Warning:  Undefined variable $print_subtotals in /usr/local/www/timetracker/WEB-INF/lib/ttReportHelper.class.php on line 1556, referer: https://timetracker.dalescott.net/report_send.php
[Mon Dec 16 09:29:45.108631 2024] [php:warn] [pid 61378] [client 162.223.103.50:33503] PHP Warning:  Undefined variable $print_subtotals in /usr/local/www/timetracker/WEB-INF/lib/ttReportHelper.class.php on line 1422, referer: https://timetracker.dalescott.net/report_send.php
[Mon Dec 16 09:29:45.108654 2024] [php:warn] [pid 61378] [client 162.223.103.50:33503] PHP Warning:  Undefined variable $print_subtotals in /usr/local/www/timetracker/WEB-INF/lib/ttReportHelper.class.php on line 1556, referer: https://timetracker.dalescott.net/report_send.php
[Mon Dec 16 09:29:45.108665 2024] [php:warn] [pid 61378] [client 162.223.103.50:33503] PHP Warning:  Undefined variable $print_subtotals in /usr/local/www/timetracker/WEB-INF/lib/ttReportHelper.class.php on line 1422, referer: https://timetracker.dalescott.net/report_send.php
[Mon Dec 16 09:29:45.108689 2024] [php:warn] [pid 61378] [client 162.223.103.50:33503] PHP Warning:  Undefined variable $print_subtotals in /usr/local/www/timetracker/WEB-INF/lib/ttReportHelper.class.php on line 1556, referer: https://timetracker.dalescott.net/report_send.php
[Mon Dec 16 09:29:45.108700 2024] [php:warn] [pid 61378] [client 162.223.103.50:33503] PHP Warning:  Undefined variable $print_subtotals in /usr/local/www/timetracker/WEB-INF/lib/ttReportHelper.class.php on line 1422, referer: https://timetracker.dalescott.net/report_send.php
[Mon Dec 16 09:29:45.108730 2024] [php:warn] [pid 61378] [client 162.223.103.50:33503] PHP Warning:  Undefined variable $print_subtotals in /usr/local/www/timetracker/WEB-INF/lib/ttReportHelper.class.php on line 1556, referer: https://timetracker.dalescott.net/report_send.php
[Mon Dec 16 09:29:45.108738 2024] [php:warn] [pid 61378] [client 162.223.103.50:33503] PHP Warning:  Undefined variable $print_subtotals in /usr/local/www/timetracker/WEB-INF/lib/ttReportHelper.class.php on line 1562, referer: https://timetracker.dalescott.net/report_send.php