Example on AA98 delay TONIGHT is in the detailed status of EF:
5ORD/6ORD-LHR NRML 772M WL OPT IN 772A SEATING 16/194/37 ACCT EDM
N7AS ORD
FTWDP R.A.BORSOS *2058
7ORD/AUTO REACCOM DLY FLT COMPLETED SEE N*P1AA0098ORD30JUL *2202*CRCYMG
3ORD/ETD2315 MTR-DELAY DUE TO A/C MAINTENANCE *2258
2LHR/PRE1243 *2258
So looks like they sub'd to a legacy 777-200 (non 772 retrofit cabin) and that it also had maint still on the sub aircraft.