[touggourt]

> The sync client on desktop said it was fully synced. Only 200GB of 800GB was on the machine.

Did you read the manual? It is recommended for such size to do the first sync using rsync (or similar) followed by the CLI command to build the files database.

[BrandoElFollito]

A service that manages data cannot fail on such things. Nextcloud could refuse this first sync and point to solutions but losing data just "because the manual says rsync" is not acceptable

[touggourt]

You're right.

[mort96]

Silent data loss like that is not acceptable, even if there would have been a way to sync which would have worked around the data loss bug.