Max,
How sure can we be of the 23 November date? I found a B-17, 42-38015, (92nd BG, 327th BS) MACR 7565 that crash landed at Mittenwald near Garmsich on 16 July 44. The crew of 9 were all captured.
I also found this account of a single plane from the 461st BG, bombing near Garmisch at Haiming on 25 November 1944.
http://www.461st.org/Liberaider/PDFs/June%201997.pdf
Mission No. 141
25 November 1944
Target: West Marshalling Yard, Munich, Germany
For the last mission of the month, which was flown
on 25 November, the Group went back again to the
west Marshalling Yard at Munich, Germany. This,
however, was a night mission, the first one ever to be
flown by the Group. The three individual planes on
the mission were piloted by Lt. Barnes, Lt. Hess, and
Lt. Miller. Two of the planes, feeling that the
nine-tenths cloud coverage in the target area warranted them sufficient protection against possible enemy fighters and searchlights, bombed the marshalling yard by the pathfinder method.
The third plane, flown by Lt. Barnes, developed oxygen leaks which necessitated the bombing of Haiming, Austria, as a target of opportunity.
Here is how the 15th AF chronology describes the above event.
SATURDAY, 25 NOVEMBER 1944
STRATEGIC OPERATIONS (Fifteenth Air Force):
During the night of 24/25 Nov, 40+ B-17s and B-24s bomb the Linz benzol
plant, Klagenfurt, and Innsbruck, Austria, and Munich W W marshalling yards in
Germany,
and 2 unidentified targets of opportunity; during the day P-38s fly
photo and weather reconnaissance missions.
I think you can see the difficulty of finding an attack on Garmisch as it probably will not be named, just a target
of opportunity, just as this attack on Haiming is described.
As you have no doubt seen, on 23 November 1944 the 15th AF was bombing in Yugoslavia. On dates around the 23rd, there were missions to Munich or Innsbruck such as the one listed above in which a single plane may have hit targets at/near Garmisch as a target of opportunity.
From the official record of the 15th AF for:
23 November 1944
STRATEGIC OPERATIONS (Fifteenth Air Force):
** In Yugoslavia, 81 B-24s attack road and railroad bridges at or near Zenica,
Brod, and Doboj; 30 P-38s bomb the Doboj marshalling yard, 13 hit Doboj road
and rail bridge, and 4 attack, but miss, a bridge at Maglaj; 13 B-24s and B-17s
drop supplies at points in Yugoslavia.