spring activiti config not kicking of async task

[kam]

Recently started using activiti first, apologies if I am not using right terms

I have a sample workflow definition using spring-boot version of activiti, followed this - Getting started with Activiti and Spring Boot . I have all tasks as activiti:async="true" and I see them kicking off. Using in-memory h2.

However, I have now configured activiti under an existing spring project as per Activiti User Guide , engine is coming up fine, connecting to an oracle database. I can start a process, I can see db entries, however the async task is not getting triggered. Can somebody give me a pointer to look for?

Unfortunately I am not allowed paste any code/config, apologies for that. however I can surely answer any specific question. 

Appreciate it.

[kam]

Just a note, it works just fine if I make them synchronous