I tried to reproduce really quick, and it is rendering when doing my test. Few questions:
-the start channel for the sub-tree is set at start channel +6*75*3, correct?
-when that effect is supposed to be played, is there anything being played on the 'master'-tree (or it's layers)
-what are the effects that are playing at the same time in the layers of the sub-tree?
The Megatree is 2700 pixels, 8100 channels, starting at channel 1711. The inner matrix starts at channel 3061, exactly like your calculations of +6*75*3.
There is nothing on the master tree
There are pictures, morphs, and other effects below the text effects.
This is specific to this one XML sequence file. I have reimported the SUPERSTAR file by itself in a new sequence and everything renders perfectly. In the problem sequence, all of the effects other than the text render perfectly.
I ran the Check Sequence routine and its not coming up with any problems, other than the overlapping channels of the inner matrix and the whole tree... no overlapping effects.
I'm guessing (with no proof or advanced understanding) that something in the XML sequence file got corrupted somewhere.