Hi @Stuart,
You are very close to the solution, the line you need to change is issue_key_column = "customfield_16400" to this one issue_key_column = “jpoh_parent_3”.
[[jira.issue_link_field_dimensions]]
name = "Feature Release"
source_dimension = "Fix Version"
issue_key_column = "jpoh_parent_3"
group = "Linked issue dimensions"
There is also the possibility to use different levels from Portfolio with this line - jpoh_parent_3, the number at the end is counted like this:
best,
Gerda //support@eazyBI.com