[TYPO3-mvc] magic functions findByProperty/countByProperty not working in FrontendUserGroupRepository?

[Genser]

ok, so the question in the subject line is answered: both functions work.

Setting the Storage Page ID (either in TypoScript, or the plugin properties) is important (Thank you Sebastian). It also seems to work without setting then StoragePid if your storage page is the first folder in your TYPO3 page tree (lowest UID).

But shouldn't it also be possible to set the StoragePid in code, for example like this:

$querySettings =
   \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance('\\TYPO3\\CMS\\Extbase\\Persistence\\Generic\\Typo3QuerySettings');
//$querySettings->setRespectStoragePage(TRUE);
$querySettings->setStoragePageIds(array($idp_folder));  // $idp_folder containt my StoragePid
$query = $this->frontendUserGroupRepository->createQuery();
$query->setQuerySettings($querySettings);

And then my original code snippet? But I can get that to work.

btw, my intent is to use this code in a function that gets called to the ['felogin']['logout_confirm ed'] hook (and I don`t know yet how to use TypoScript there, if it is at all possible).