Question pool: cannot open a question

<dispatchinfo>
	<componentinfo>
		<compname>ffo_main_item_list</compname>
		<compclass>org.olat.core.gui.components.form.flexible.impl.FormWrapperContainer</compclass>
		<extendedinfo>n/a</extendedinfo>
		<event>
			<class&gt;org.olat.core.gui.components.form.flexible.impl.elements.table.SelectionEvent</class&gt;
			<command>quick-view</command>
			<tostring>com:quick-view,org.olat.core.gui.components.form.flexible.impl.elements.table.SelectionEvent@615de2a4</tostring>
		</event>
	</componentinfo>
	<controllerinfo>
		<controllername>org.olat.modules.qpool.ui.QuestionListController</controllername>
		<controllername>org.olat.modules.qpool.ui.QuestionPoolMainEditorController</controllername>
		<controllername>org.olat.core.commons.fullWebApp.BaseFullWebappController</controllername>
	</controllerinfo>
</dispatchinfo> 
Throwable: org.olat.core.logging.AssertException

logmsg:could not set to true because key was not found!
message:could not set to true because key was not found!,org.olat.core.logging.AssertException
 at org.olat.core.gui.components.form.flexible.impl.elements.SelectboxSelectionImpl.select(SelectboxSelectionImpl.java:227)
 at org.olat.modules.qpool.ui.metadata.GeneralMetadataEditController.initForm(GeneralMetadataEditController.java:110)
 at org.olat.core.gui.components.form.flexible.impl.FormBasicController.initForm(FormBasicController.java:278)
 at org.olat.modules.qpool.ui.metadata.GeneralMetadataEditController.(GeneralMetadataEditController.java:90)
 at org.olat.modules.qpool.ui.metadata.MetadatasController.(MetadatasController.java:67)
 at org.olat.modules.qpool.ui.QuickViewMetadataController.setItem(QuickViewMetadataController.java:63)
 at org.olat.modules.qpool.ui.AbstractItemListController.formInnerEvent(AbstractItemListController.java:339)
 at org.olat.modules.qpool.ui.QuestionListController.formInnerEvent(QuestionListController.java:369)
 at org.olat.core.gui.components.form.flexible.impl.FormBasicController.event(FormBasicController.java:430)
 at org.olat.modules.qpool.ui.QuestionListController.event(QuestionListController.java:414)