Changing pipe service changes the service for unrelated piping

[_Jeff_Roy_]

Per the title, I've got several piping models that were initially modeled without line numbers assigned (service, area, etc.). I'm now going back and updating these lines to assign the service and have noticed that if I update one line or even one component, the model is automatically changing the service of many other unrelated, unconnected pipe components. For example, I could place a new, random elbow somewhere in space and modify the assigned service for that component. This results in several other lines and components having their service modified to match the new component. There is no physical connection between the new component and other components. The reason I'm able to quickly notice that the service has been modified elsewhere in the model is because I have my layer color settings configured to be based on service code.

Any theories / suggestions on how I might prevent this from happening?

[jabowabo]

Are you updating the Service value in the Properties palette? You should be assigning a tag before updating any other Process Line properties. Items that have an 'Unassigned' Line Number Tag value can be grouped (seemingly) randomly. You'll get unpredictable results if you change these properties before assigning a Line Number Tag.