When using custom VSM MQ steps, the VSE is processing transactions fine, but in the DevTest Console shows VSE Transaction Count as zero always.
The reason you are not seeing transaction count in the model is that, a change was made sometime in the 8.x-9.x time frame that basically means VSE only counts transactions when the VSM-based steps are used. The code that increments the transaction count now looks for a special testExec property that those steps set.
If a VSM is not recorded one or uses deprecated IBM MQ publish /consume steps and if it has custom Java script steps you face this issue.
DEVTEST versions 8.x , 9.x and 10.x affected
Here is something you can do to the existing model :
Include the following line in your script step just before the respond step and that should update the Transaction count.