The MV84X uses the Multicam license, which is different from the standard MV license used by most other Meraki cameras. This license is tailored for advanced features such as multi-sensor video streams and higher performance.
According to Cisco documentation, Cloud Archive is compatible with all MV models, but I noticed that the MV84X is not explicitly listed among the models in the detailed Cloud Archive compatibility table.
MV Cloud Archive - Cisco Meraki Documentation
https://documentation.meraki.com/MV/MV_Datasheets/MV84X_Datasheet
I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.
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