I don't know if anyone knows about this but if you have a utility plan base that is being xref into a utility plan and you do a swap parts, all the labels on that pipe network will be reset.
For example. i have a just about completed my storm plan. Then i later decide do a swap part on one my pipes on my storm base and hit save. all the storm labels for that pipe network will be reset on my storm plan when i do the xref update. you will have to go back and drag your labels to the locations you had them before. The only way to get around this is to either label your utiltity pipes and structures on your storm base or data reference the pipe network into your storm plan. Yeah this sucks a little.