Why do rights to user shares disappear when owncloud is updated?

Question

ownCloud/Nextcloud

Hello.
I update owncloud from version 10.0.3 to version 10.2.1 (I also tried it to 10.1.0)
, I do the update manually according to the instructions from the off site and there are no problems during the update itself.
But after the update, all connections are lost. i.e. users see only their own files, and everything that someone has shared with them, other people's shared, shared folders do not see.