Using the expression Current cell's index can be very handy at times on repeating groups. The problem is, when a group is then added into a cell of a repeating group, it appears the Current cell's indexexpression disappears from the list, not being available to select.
While this is true, its not available in the list, you can still copy the dynamic expression and paste in where needed e.g. content, conditions, workflows…
Here is a hacky workaround, that appears to be working fine as it stands of this post date:
Current cell's index doesn’t appear in the list - this text element is inside 2 parent groups
Here we copy the working expression of
Current cell's index inside the root of the rg
Then, we can paste the expression into a element
Dynamically this expression appears fine and doesn’t flag as an app error
Can be used on a condition example
Result of the above rendered
Example of workflow use