Make sure you allow yourself to assign ID attributes to you app.
Inside a repeating group, put this element inside the cell. You can hide it however you want. Just make sure it is visible when your group items load.

Setting up a conditional for it to show when the RG items are loaded is the best way I found so far.

Assign dynamic ID's to your element ID fields on the properties.

Take a look at the demo for more detailed instructions.