For anyone looking for an alternative to the count() function to autonumber rows, I figured one out.
Create a field, "ItemCount", and set the default value to 0 or 1 depending one how your groupings are set up. Uncheck the refresh when form recalculates. Now create another field in your repeating group. Let's call it "row". Set the default value of "row" to "ItemCount" and again make sure the refresh when form recalculates is off. Now make an action rule on that "row" field. Set the field's value of "ItemCount" to "ItemCount" + 1.
I know that this is quite more steps than the count() function method but if you absolutely need to not use count(), then this is your work around. Hope this helps.