Thanks for all your help with this issue.
I’ve done some debugging and found the issue!
This is a very specific case which is caused by a specific version of ACF PRO (v5.1.7, v5.1.8) + tab/repeater field using the same name.
This problem has been fixed in v5.1.9, so firstly, please update to the latest version.
The next thing to do is delete and re create your tab fields.
They can use the same names, but by re-createing them, the tab fields won’t conflict with the loading of values and will allow your repeater field to work again!
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