Hi Mike,
In current source code we don't have this class: AseBulkCopyBusinessBulk.cs. Do you have the stack and/or code snippet where the problem occurs? I see you have 15.5 ESD#12 and 15.7 ESD#4. Now that we are SAP we have 15.7 SP130 which is about 9 patch levels above the ESD#4. I don't recall that class from the older releases. It's possible since we re-implemented the bulk option to actually use real bulk library style calls to ASE some classes were revamped/renamed.
I would think using the latest release like 15.7 SP130 and then using EnableBulkLoad=1 (or 2) as dawn indicated might help. If we had the details it might also help to figure out the problem - since we don't have that class, whatever the fix would be to it won't apply to current codeline.
Cheers,
-Paul