Marvel 1.3.1 unable to collect stats from Cluster

Hi:
My Cluster Configuration is as follows:

running ES ver. 1.5.2
3 data nodes (http.enabled:false)
2 Client nodes (node.master: false, node.data:false)
I do not have a separate monitoring cluster and I am trying to collect all stats locally (which is default).
I have marvel ver. 1.3.1 installed on all nodes, I am not seeing any stats from the data nodes being collected. every second or two there are two records generated from the 2 Client nodes. I saw a bug report (reported as being fixed in 1.3.1) wherein disabling http also disabled stats collection by Marvel. however I do not see this being resolved.

Am I missing some hidden setting that needs to be enabled ?

Any and all help is much appreciated.

Thanks much

Ramdev