Cannot connect with new Firefox Profile

Hello
I tried both, connecting via QR-Code (mobile -> Laptop) and via Link. Both give me following errors:

{“reqId”:“hCrl4C820NejFsHdOsDs”,“level”:4,“time”:“2021-02-19T15:50:04+01:00”,“remoteAddr”:“31.18.131.59”,“user”:“Ray-Ven”,“app”:“passwords”,“method”:“GET”,“url”:"/index.php/apps/passwords/link/connect/await",“message”:{“Exception”:“OCP\AppFramework\Db\DoesNotExistException”,“Message”:“Did expect one result but found none when executing: query “SELECT * FROM *PREFIX*passwords_entity_registration WHERE (deleted = :dcValue1) AND (user_id = :dcValue2) AND (uuid = :dcValue3)”; “,“Code”:0,“Trace”:[{“file”:”/var/www/html/nextcloud/lib/public/AppFramework/Db/QBMapper.php”,“line”:346,“function”:“findOneQuery”,“class”:“OCP\AppFramework\Db\QBMapper”,“type”:"->"},{“file”:"/var/www/html/nextcloud/apps/passwords/lib/Db/AbstractMapper.php",“line”:201,“function”:“findEntity”,“class”:“OCP\AppFramework\Db\QBMapper”,“type”:"->"},{“file”:"/var/www/html/nextcloud/apps/passwords/lib/Db/AbstractMapper.php",“line”:174,“function”:“findOneByFields”,“class”:“OCA\Passwords\Db\AbstractMapper”,“type”:"->"},{“file”:"/var/www/html/nextcloud/apps/passwords/lib/Db/AbstractMapper.php",“line”:99,“function”:“findOneByField”,“class”:“OCA\Passwords\Db\AbstractMapper”,“type”:"->"},{“file”:"/var/www/html/nextcloud/apps/passwords/lib/Services/Object/AbstractService.php",“line”:100,“function”:“findByUuid”,“class”:“OCA\Passwords\Db\AbstractMapper”,“type”:"->"},{“file”:"/var/www/html/nextcloud/apps/passwords/lib/Controller/Link/ConnectController.php",“line”:303,“function”:“findByUuid”,“class”:“OCA\Passwords\Services\Object\AbstractService”,“type”:"->"},{“file”:"/var/www/html/nextcloud/apps/passwords/lib/Controller/Link/ConnectController.php",“line”:166,“function”:“getRegistrationFromSession”,“class”:“OCA\Passwords\Controller\Link\ConnectController”,“type”:"->"},{“file”:"/var/www/html/nextcloud/lib/private/AppFramework/Http/Dispatcher.php",“line”:169,“function”:“await”,“class”:“OCA\Passwords\Controller\Link\ConnectController”,“type”:"->"},{“file”:"/var/www/html/nextcloud/lib/private/AppFramework/Http/Dispatcher.php",“line”:100,“function”:“executeController”,“class”:“OC\AppFramework\Http\Dispatcher”,“type”:"->"},{“file”:"/var/www/html/nextcloud/lib/private/AppFramework/App.php",“line”:152,“function”:“dispatch”,“class”:“OC\AppFramework\Http\Dispatcher”,“type”:"->"},{“file”:"/var/www/html/nextcloud/lib/private/Route/Router.php",“line”:309,“function”:“main”,“class”:“OC\AppFramework\App”,“type”:"::"},{“file”:"/var/www/html/nextcloud/lib/base.php",“line”:1008,“function”:“match”,“class”:“OC\Route\Router”,“type”:"->"},{“file”:"/var/www/html/nextcloud/index.php",“line”:37,“function”:“handleRequest”,“class”:“OC”,“type”:"::"}],“File”:"/var/www/html/nextcloud/lib/public/AppFramework/Db/QBMapper.php",“Line”:270,“CustomMessage”:"Did expect one result but found none when executing: query “SELECT * FROM *PREFIX*passwords_entity_registration WHERE (deleted = :dcValue1) AND (user_id = :dcValue2) AND (uuid = :dcValue3)”; "},“userAgent”:“Mozilla/5.0 (Android 8.0.0; Mobile; rv:85.0) Gecko/85.0 Firefox/85.0”,“version”:“20.0.7.1”,“id”:“602fd01caf903”}

In the extensions debug dialog it says
Passwordsclient not found
no defaults configured

The app itself works on another firefox account - not on the fresh created one

Do you have any hints?

NC 20.0.7
Passwords 2021.2.0
using php 7.4