Comprehensive and Detailed Explanation From Exact Extract:
For a transformer to correctly process and display a value, the custom poller used for transformation must be assigned to the same node; otherwise, the transformation cannot occur. Additionally, both the custom poller and the transformer must have the same polling interval to ensure synchronized data collection and processing. If their intervals do not match, the transformation can fail or display incorrect results.
Reference:
Universal Device Poller Admin Guide, "Requirements for Transformers and UDP Assignments,"
"Transformer values are only available if the associated pollers are assigned to the same node and are using the same polling interval."