Cross-Chain Roundtrip Message Returns Empty String Instead of 'Hello World!'

[dianalokada]

When attempting a cross-chain message roundtrip using the SenderOnCChain and ReceiverOnSubnet contracts, the roundtripMessage() function on the SenderOnCChain contract returns an empty string instead of the expected "Hello World!" message.
Expected Behavior:
-SenderOnCChain sends "Hello" to ReceiverOnSubnet.
-ReceiverOnSubnet receives "Hello", appends " World!", and sends "Hello World!" back.
-SenderOnCChain receives "Hello World!" and stores it in the roundtripMessage variable.
-Calling roundtripMessage() should return "Hello World!".

Actual Behavior:
Calling roundtripMessage() returns an empty string "".

[SwarnaIslam]

Facing same issue. When I remove the sending response part from ReceiverOnSubnet, it is working just fine. But seems like adding the sending response part causes reverting or something.(?) Please let me know if you have solved the problem.