[xwiki-users] Global user rights lost when saving on subwiki XWikiPreferences

Hi all, After upgrading from 4.4.1 to LTS 6.4.4 it seems that something gets messed up with global user rights on subwikis. If I perform a save on XWikiPreferences page of the subwiki (via Administer Wiki), global users lose access (at least view rights) on this subwiki. These rights are restored automatically (something gets refreshed?) if I do some of the following: * Modify anything in rights section both in global wiki and subwiki, even if it does not affect user directly: for example, adding/removing a user/subgroup to the group of the problematic user * Save anything on user's profile (password, email...) * Re-set again user's rights or user's group rights Pitifully those rights are lost, once again, when saving on XWikiPreferences page. This does not happen for local users neither if I perform a save on other subwiki pages. Perhaps related to this, after upgrading, local users are no longer able to see the left panels I'm using on subwiki, but global users do. What might be happening? Greetings, Iago