I think it's your Jetstar segment for DPS-SIN, while it should be allowed on a DGLOB34, it may be the hiccup. The tool doesn't like economy segments sometimes.

Try changing that to DPS-HKG-SIN or DPS-KUL-SIN and see if it prices. If that still fails it might be the DRW-DPS as well but there aren't great alternatives for that since you'll already have used your allotted Australia transcon on SYD or BNE-DRW.

If you call AA's RTW desk they should be able to ticket it as a DGLOB34 as you have it (or from OSL-LHR-ORD with the 2000 euro savings), they'll want their code on the LHR-ORD and / or DFW-SYD to ticket it, but that should be a much lower YQ than prime BA or QF codes on those two anyway.