I’ve just tested it on my end, and it was working as it should be. One issue that I see with your setup is that you have a very long name for your repeater and its subfields. Could you please rename it to something shorter? This page should give you more idea about it: https://www.advancedcustomfields.com/resources/field-value-wont-save/.
Also, could you please make sure that no other function in your plugins and theme caused it? To do it, you can try to reproduce the issue on one of the WordPress’ stock themes (like Twenty Fifteen) with only ACF activated.
I hope this helps 🙂
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