I have seen "odd" errors occur before for other API's that worked when run in smaller batches.
It could be something as simple as a buffer cache issue, in that the size of the data file being processed is too big to do in one hit.
From a sheer manageability point of view, i'd not run in a single batch of 50k records in one hit anyway. I'd always break it down into smaller chunks to process in Web ADI.
Regards
Barry
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