Hi Laura, thanks for your question.
Workforce does not currently support an offline mode; but that is in our roadmap to support. We are targeting the second half of this year.
If a user looses network / wifi connection while using the Workforce app; they will still have access to their assignments in a read-only manner, until they establish their network / wifi connection.
It's on our roadmap for 2018. We're tentatively planning it for around User Conference.
I've got your details in our Offline issue in the Workforce repo, so you'll be hearing from us as we get closer to having something to test.
It the main driver for our next release and the team is currently working on it.
See our recent blog update for 10.6.1 support where we reference it:
We have an update on the timeline for the next release of Workforce.
Our current timeline is Q3 for this next release. We are planning a series of private tech previews; which will support Enterprise 10.7/10.7.1 around the end of May.
If you're interested in participating in the tech preview, please contact us at email@example.com