Save data from repeating group with external button

[bartek.dev]

I had the same issue, and the solution was to use Orchestra plugin

Have a look at this topic and the editor

How to iterate on a list based on states from within "current" cell?

Thanks @boston85719. Yes you were right. Orchestra can trigger workflow from within the cell so I can access the cell states. For those interested the editor below has the solution using Orchestra plugin.