We took an additional $2,900 from our IRA and converted the $2,900 to a ROTH IRA. Within Turbo Tax I declared all $2,900 to not be an RMD and Turbo Tax is now asking for a form 5498, but the managers at American Funds say I'm not getting one as none of our activity has generated the need for one.
Did you try and enter something under the Retirement contributions section?
TurboTax does not specifically ask for a Form 5498. TurboTax only indicates that Form 5498 is a place that you can find the amounts contributed to a particular IRA for the year.
The Roth IRA custodian most certainly must issue you a 2018 Form 5948 from the Roth IRA showing the conversion contribution (assuming that this occurred in 2018). However, it's not required to be issued until sometime in May, so to be able to file by April 15 you'll likely need to use your own records to determine the amounts to enter in response to the follow-up questions to entering the Form 1099-R.