Terrain shifting in profile

Good afternoon.

My company is working on a large project (approximately 26 miles).  We've broken the project up into nine segments.  The start station for each segment begins at an even thousand.  Segment 1 begins at 1000+00.  Segment 2 begins at 2000+00.  This continues throughout the project for all segments.

We needed to make a change to the segment break between Segment 5 and Segment 6.  Segment 5 had to be extended to the east approximately 500'.  Segment 6 was shortened that same 500'.  This caused the end station for Segment 5 to change from 5105+22.84 to 5110+22.84 and the start station for Segment 6 to change from 6000+00.00 to 6005+00.00.  

We wanted the starting station for Segment 6 to remain at 6000+00.00.  We used the "Geometry > Horizontal > Modify > Start Station" command to change the start station back to 6000+00.  Everything in the plan view appears correct but when we look at the profile the existing ground appears to have shifted by 500'.  The file containing the terrain has not changed.  Within Reference Manager, the scale, offset and rotation settings for the file containing the terrain model have not changed. 

Has anyone else had this happen?  Is there something we're missing that's causing the terrain to have shifted?

<<Late edit>>  We are using OpenRoads Designer CE 2021 Release 1, Version 10.10.1.3