I just set up a ManyManyDataObjectManager instead of the complextablefield and I am having the strangest issue ever.
The object in question inherits Sitetree directly so the fields I've got access to are the ones in the Sitetree table.
Now if I set the field to anything but Title, it displays the value from that field but if I set the value to Title it displays the id with a # in front.
Right now it looks like this and it works the way you'd expect. However if I switch out URLSegment for Title it all goes bonkers. If I grab the tables ID or anything else that works fine as well.
$modulesTablefield = new ManyManyDataObjectManager(
'URLSegment' => 'Title', 'Created' => 'Created'
$modulesTablefield->setAddTitle( 'A Product' );
Wow.. Thank God for SVN. I was able to track down the change I made several months ago and see that, while it had been applied to MMDOM, i had pasted it in above the old code rather than replacing it, so it was running correctly, then undoing itself.