Thanks for letting us know.

Do you know if Day End Processing had been run in OE? It might be that items recently invoiced but not yet processed could have an effect, because these items would have 'qty shipped not costed' and perhaps the calculation on the re-order report isn't taking this into consideration.

Just a guess as to why only recent orders might be affected.

If the report works (albeit not with all expected items), but then is correct later on, then some data condition - perhaps just a matter of timing - is the likely culprit. Not corrupt data, only the values for quantities.