What's the go here. The DM10 is suppose to 64 note polyphonic no?
Yes, but your issue has nothing to do with the polyphonic limit. It is a Xtalk issue.
I get the same issue with Snare Head and Snare Rim. If i play them both only one sounds.
In the DM10 there is a special Xtalk parameter for dual zone inputs called "Zone talk". "Zone talk" is a setting that allow the user to restrict adjacent zones (i.e. Snare Rim and Snare Head) from triggering at the same time. If you want the adjacent zones to be able to trigger at the same time, you need to set zone talk to "0". Once you do that, you should be able to play both zones at the same time.
If i then play the snare RIM and Tom 1, only one of them will sound. This issue seems intermittent depending on how exactly i play both. If i am just a fraction out then both sound. But if I am exactly in unison one will not trigger. In this case usually Tom 1 stops.
This issue I think is just a regular Xtalk issue (meaning some Xtalk parameter is set too high), but to be honest I don't think I've ever played the snare rim and Tom 1 head at the same time. I have played the Tom 1 rim and snare head at the same and never had this issue. I normally have a cow bell set to Tom rim 1, so hitting Tom rim 1 and the snare head at the same time happens a lot.