RX2 data rate change for OTAA class c device


I have been evaluating ChirpStack (docker). I’m having a problem with updating the RX2 data rate for my test device to DR3. The server is running EU868 using the regional params from v1.0.2. I have searched the forum for posts about RX2 data rate issues. From the posts I get the idea that ChirpStack only supports an initially set RX2 data rate for OTAA (from chirpstack-network-server.toml or if unset taken from the regional param settings). Is this correct and if yes then why?