Hi @Monet ,
Do you want to pass the values from your app to your flow to send an email?
Could you please share a bit more about the Flow connection formula ('FlowName'.Run(...)) within your app?
Based on the issue that you mentioned, I think there is something wrong with your Flow connection formula. Currently, the MS Flow could only accept Text string parameter passed from PowerApps app, it could not pass an record value from an app to a flow.
Within your Flow connection formula, you should modify the dropdown/Choice field value reference as below:
SharePointForm1.LastSubmit.'<dropdownFieldHeader>'.Value /* <-- append .Value formula here */
or
SharePointForm1.LastSubmit.'Choice Field'.Value
Please take a try with above solution, then check if the issue is solved.
Best regards,