Let's assume you have a REST custom connector where you have PATCH operation. When that is called from a button, it is returning 202OK (also tested with 204) and error 'The data returned in the response is invalid' is showed in PowerApps.
Exactly the same service from the connector works in Flow. It seems that PowerApps care about the response and do not like 202/204 status coded for PATCH/PUT operations.
Can you please fix it, it is annoying.
Thank you.
Tomas