Could not complete Workflow Step in AEM 6.2
I have created a workflow in AEM 6.2 where I am having a AND split, which is having 2 branches, each branch is having a dialog participant step. Workflow looks like below:

In dialog participant step, I have created a dialog which is having a dropdown field added.

When I am running this workflow on a page, I am able to complete mcr branch but when I am completing other branch [brand], I am getting error as “Could not complete workflow” and control does not go to qc step the last one. Can someone please help on how to resolve the issue.