Pegasus plan fails on container task clustering

Pegasus plan fails when I try to cluster container tasks based on label.
Same thing happens with docker and singularity.

Error msg:
2018.10.25 16:40:23.276 PDT: [FATAL ERROR]
 [1] java.lang.RuntimeException: null at edu.isi.pegasus.planner.refiner.MainEngine.runPlanner(MainEngine.java:207)
 [2] java.lang.RuntimeException: Cannot cluster jobs with different types of containers associated. Container for job pointalert_ID0000012 - cont casa_image{
type docker
image file:///nfs/v5/georgpap/scratch/CASA-Workflow/bin/casa-app.tar
image_site condorpool
}
does not match with job mvt_ID0000011 - cont casa_image{
type docker
image file:///nfs/v5/georgpap/scratch/CASA-Workflow/bin/casa-app.tar
image_site condorpool
}
 at edu.isi.pegasus.planner.cluster.aggregator.Abstract.constructAbstractAggregatedJob(Abstract.java:317)

A version of this workflow can be found at workflow.isi.edu, in the following folder: /nfs/v5/georgpap/scratch/CASA-Workflow