I have a design in DxDesigner (PADS 9.5) and after renumbering the components when doing a back annotate, the REFDES are remaining the same on the schematic, however the other properties of the symbol are changing. For example I have a polarized tantalum symbol which is having its DEVICE and PKG_TYPE fields changed to a generic 0603 cap, the PART_NUMBER, TOLERANCE, VALUE, and VOLTAGE did not change and the symbol remained the tantalum as well as the REFDES staying the same. The values that did not change, are not part of the actual symbol. Meaning, we have a symbol for a certain sized part and the PART_NUMBER, TOLERANCE, VALUE, and VOLTAGE were manually added to the component.
It acts like the refdes was the key for
The only thing that seems suspect in my settings is in the PCB Interface -> Advanced -> REFDES Processing / Optimization. It has the "Preserve Previous REFDES Assignments (Forward to Layout)" selected and is greyed out.
I'm not sure if it was just too much that had changed, but I ended up just manually making an ECO file to map the components (only about 160 caps so it wasn't too awful). I think the eco data got lost somewhere along the way.