I have set the timezone in DT Register to America/Chicago.
I have set the timezone in JEvents to America/Chicago.
I have set the timezone in Joomla itself to America/Chicago
Then I tried every combination of having the set or not set.
When I create a new event that is sync'ed with a JEvent, the time in DT Register is one hour earlier than it should be.
DT Register 2.7.17