I'm successfully using reference tags with MQTT data on store/forward, but the catch is that all data must be flushed in chronological order, and the history settings require minimum time between samples set to 0.
See this article for details (there's others as well in the menu to get more info): MQTT History Back-Fill with Reference Tags - MQTT Modules for Ignition 8.x - Confluence
Here's another one that explains more as well: MQTT History - MQTT Modules for Ignition 8.x - Confluence