It has been an extremely long time since I’ve worked with ACF4. The only thing that I remember is that the function names used for repeater loops is different. I’m not even sure the documentation I found it the internet archive is the correct documentation. It could be that I found older or newer information than you need.
More than likely, if this was me, I would download the plugin files for the repeater and I’d dig through that code to see how the code you have is actually working. Of find another repeater that is working and see how it is working.
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