Did you check "adjust contract exchange" (I don't remember the exact wording) on the futures page? The same problem also exists on bonds and ES if this option is not checked.
Probably the contract adjustment wasn't done correctly. I suppose it can be done in excel by setting the closing price on the adjustment day the same.
The volume is always a problem ... this is similar to small cap stocks.
However, small caps also tend to have longer trend due to their unpopularity. The same can be said about these small assets. It is very rare to have a popular asset like 6J in trend for so long. I guess it has never happened before.