Null error trying to set monitoring rules

[loveshack]

I've updated to all the latest debs (icingaweb2 2.13.0-1+ubuntu24.04, icinga-vspheredb 1.8.1-1+ubuntu24.04, all dependencies up-to-date) to fix #616 (thanks), but now get this traceback when trying to define monitoring rules. This is setting up vspheredb from scratch. I don't do PHP, but can take debugging suggestions or provide more info. It's with vcenter 8.0.3 in case that's relevant.

ipl\Html\FormElement\SelectElement::getOption(): Argument #1 ($value) must be of type string|int, null given, called in /usr/share/icingaweb2/modules/vspheredb/library/Vspheredb/Monitoring/Rule/RuleForm.php on line 173 (SelectElement.php:38)

#0 /usr/share/icingaweb2/modules/vspheredb/library/Vspheredb/Monitoring/Rule/RuleForm.php(173): ipl\Html\FormElement\SelectElement->getOption()
#1 /usr/share/icingaweb2/modules/vspheredb/library/Vspheredb/Monitoring/Rule/RuleForm.php(267): Icinga\Module\Vspheredb\Monitoring\Rule\RuleForm->setInheritedValue()
#2 /usr/share/icingaweb2/modules/vspheredb/library/Vspheredb/Monitoring/Rule/RuleForm.php(79): Icinga\Module\Vspheredb\Monitoring\Rule\RuleForm->addEnabledSetting()
#3 /usr/share/icinga-php/ipl/vendor/ipl/html/src/HtmlDocument.php(286): Icinga\Module\Vspheredb\Monitoring\Rule\RuleForm->assemble()
#4 /usr/share/icinga-php/legacy/gipfl/web/src/Form.php(46): ipl\Html\HtmlDocument->ensureAssembled()
#5 /usr/share/icinga-php/ipl/vendor/ipl/html/src/Form.php(249): gipfl\Web\Form->ensureAssembled()
#6 /usr/share/icingaweb2/modules/vspheredb/application/controllers/MonitoringController.php(263): ipl\Html\Form->handleRequest()
#7 /usr/share/icingaweb2/modules/vspheredb/application/controllers/MonitoringController.php(158): Icinga\Module\Vspheredb\Controllers\MonitoringController->showType()
#8 /usr/share/icinga-php/ipl/vendor/icinga/zf1/library/Zend/Controller/Action.php(528): Icinga\Module\Vspheredb\Controllers\MonitoringController->vmrulesAction()
#9 /usr/share/php/Icinga/Web/Controller/Dispatcher.php(78): Zend_Controller_Action->dispatch()
#10 /usr/share/icinga-php/ipl/vendor/icinga/zf1/library/Zend/Controller/Front.php(954): Icinga\Web\Controller\Dispatcher->dispatch()
#11 /usr/share/php/Icinga/Application/Web.php(296): Zend_Controller_Front->dispatch()
#12 /usr/share/php/Icinga/Application/webrouter.php(107): Icinga\Application\Web->dispatch()
#13 /usr/share/icingaweb2/public/index.php(4): require_once('...')
#14 {main}