Delete share over email

Nextcloud version : 15.0.2
Operating system and version Ubuntu 18.04 - buster/sid
Apache or nginx version Nginx 1.14.0-0ubuntu1.2
PHP version PHP 7.2.10-0ubuntu0.18.04.1

i have problem with delete share folder over mail.

When I share folder over email, from one user, delete share work fine
When i share folder for second NextCloud user, this second user reshare this folder over mail, shared over email don’t delete any users.

I see into database this share, when i delete row manualy, share is deleted.

On nextcloud 12 work fine.

Thank you for answer

Error : PHP

[PHP] Error: TypeError: Argument 3 passed to OC\Activity\Event::setObject() must be of the type string, null given, called in /var/www/html/nextcloud/apps/sharebymail/lib/ShareByMailProvider.php on line 323 at /var/www/html/nextcloud/lib/private/Activity/Event.php#377

DELETE /ocs/v2.php/apps/files_sharing/api/v1/shares/9?format=json
from by isteflova at 2019-02-05T12:28:52+00:00