Someone deleted the items, or someone left themselves logged in on a shared computer and someone else tried to start using Zotero from scratch (but that would generally result in all items being deleted).
If a group admin emails support@zotero.org with the group name, we can tell them more.
I'll have the admin email. No one deleted the items and computers were secure. The only thing I can think of is that it has to do with updating to the latest version of Zotero.
We let the admin know who deleted the items. (It was the third person in the group.)
As we mentioned, while all collections were permanently deleted, most of the items are still in the trash. You can simply restore those items.
(This was done with Zotero 7, which sends deleted collections to the trash first, so it's unclear why they permanently deleted all collections but left most items in the trash, but that's what they did.)
People sometimes do this when they're trying to free up Zotero Storage space, without realizing they're affecting others.
If you'd like to restore the collections, you or another group member may still be able to do so by restoring from one of the automatic backups Zotero makes.
Upgrade Storage
If a group admin emails support@zotero.org with the group name, we can tell them more.
As we mentioned, while all collections were permanently deleted, most of the items are still in the trash. You can simply restore those items.
(This was done with Zotero 7, which sends deleted collections to the trash first, so it's unclear why they permanently deleted all collections but left most items in the trash, but that's what they did.)
People sometimes do this when they're trying to free up Zotero Storage space, without realizing they're affecting others.
If you'd like to restore the collections, you or another group member may still be able to do so by restoring from one of the automatic backups Zotero makes.