It could be this easy mistake...
When you unzip a mod, it's usually inside a redundent folder.
Open a folder called "unzipped mod", and you will see the folder inside is also called "unzipped mod".
Open that one, and you should see the data folder.
The 'outer' or first "unzipped mod" folder is just packaging. You need to get rid of it.
Only copy the second "unzipped mod" folder (with the data inside) into your JSGME.
It should not be My Mod/My Mod/data.
Just My Mod/data.
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