[ENH] Sync before flushing (#5296)

## Description of changes

_Summarize the changes made by this PR._

- Improvements & Bug fixes
  - Calls sync_all before flushing the file
- New functionality
  - None

## Test plan

_How are these changes tested?_
Existing tests are sufficient
- [x] Tests pass locally with `pytest` for python, `yarn test` for js,
`cargo test` for rust

## Migration plan
None

## Observability plan
None, errors will bubble up

## Documentation Changes
None