Thanks for posting to the Community.
Do you have any update on this? Please share any relevant info here, it might help someone with a similar issue.
Thanks for responding - I do have an update; I raised this via the HEAT support portal and received the following response:
"...I was able to reproduce the issue you have described.
This issue will now be investigated by our engineers. You will be kept updated about the results"
Based on the response, I would infer this is not intended functionality - so fingers crossed this will work with referenced fields in the future (which would be great!)