For example the 1hr durations in P6 are increased to 28hrs. Can't work out why it would do this.
When importing from P6, make sure that the following are all set to Import (not Skip):
Synchro is interoperable with a number of different scheduling programs (Microsoft Project, Asta Powerproject and Primavera P6) so there are various reschedule settings that may need to be changed to match the rescheduling behavior of the program you are importing from.
Check the settings in Options>Gantt Chart>Rescheduling>Parameters
Also check in Options>Synchronisation>Primavera P6 that "Adjust times to GMT" is turned OFF
If these suggestions don't resolve the issue, you may send your P6 XML to firstname.lastname@example.org for investigation