We were seeing some cases where the time difference was one hour causing us to think this was a Daylight savings time issue
Our previous CAD Technical administrator and Project Leader was back on contract as a consultant and investigated, delivering the attached report. Our thought, based on this is that our problem would have gone away, or reduced in November when we returned to Standard time.
Based on this the Intergraph Support Personnel were able to find an updated "is_dst_now function" that their development team provided. I have altered the function in our development system and will test. Once I have added it to production I will report back.