Possible Egyptian Mythology Mash-up blocks.json warning

I’m playing Minecraft Bedrock on Windows with Egyptian Mythology Mash-up enabled. When loading my Egypt world, this warning appears:

[Blocks][warning]-Warning: The blocks.json "format_version" field was not given. "format_version" 1.1.0 will be used.

I suspect the mash-up pack, but haven’t confirmed it with that pack enabled alone. Please investigate.