Subscription Issue

Hi Team,

I'm trying to use subscription functionality to achieve local data sharing between the devices. For this I have the below scenario:

There is a device A which read payload from an external system(XYZ) over MQTT protocol and publish this payload over a new topic test1 and there is another lambda function B that subscribed topic test1. Both are attached in the Greengrass group. when I deployed this in-group the lambda function not able to read the topic test1 payload but when I change the subscription of Device A to AWS IoT Cloud then lambda function starts reading the publish topic payload. I don't know why this happening. Does Greengrass not support horizontal subscription.

Scenario 1:(Not Working)
topic:test1
Device A----------------> Lambda B (Not Working)

Scenario 1:(working)
topic:test1
Device A ----------------> AWS IoT Cloud
topic:test1
Device A--------------> Lambda B

Please suggest what is wrong I am doing here.

Regards,
Raj