Hi Christian,
I believe the “skip missing” option is needed in your import definition (when mapping data from your Google sheets)
https://docs.eazybi.com/display/EAZYBIJIRA/Additional+data+import+into+Jira+Issues+cube#AdditionaldataimportintoJiraIssuescube-Columnmapping
It should import rates only to epics and ignore missing entries.
Please check also this article (“Rates import for a user” part):
Martins / eazyBI support team