Backbone does not consider the inital status of a workflow mapping - and therefore an issue may be in the wrong status.
Steps to reproduce
Create a synchronization with a workflow mapping which maps the initial status of project B, e.g. Open, to some status of project A, e.g. "in progress" (it's important that it's not mapped to the initial one)
Create an issue in project B
Check the status of the issue
The status of the issue in project A should be the mapped one, e.g. "in Progress".
The status of the issue remains in the initial state, e.g. "Open"
If you perform a resync from B to A for this issue and check the "current status" checkbox, the status is properly propagated.