In FLX sync we apply changesets in bootstrap download messages across several different write transactions and update our progress cursors at the end in the last write transaction. If a modification occurs on an object that has come into view during an applied bootstrap changeset, but before all bootstrap changesets have been applied/integrated, the resulting state will end up being correct, but the server version of the changeset containing the modification will be wrong - resulting in diverging history between the server/client.