Per this page the Chinese Nationalists got their B-24M's right at the end of the war.
http://home.att.net/~jbaugher2/b24_33.html
The apparent main use was in the Chinese Civil War and from Taiwan against the mainland afterward.
Soviet MiG-15's of the 29th Guards Fighter Regiment, in air defence duty in Communist China, claimed a B-24 shot down over Shanghai the evening of May 11, 1950. It doesn't appear in this list of ROCAF losses however (as some other Soviet 1950 claims over China do). It may even have been a USN PB4Y-2 Privateer, some of which were unsucessfully attacked along the China coast in the Korean War period corresponding to claims of bombers downed. However I don't know of any specific US reference to this pre-KW incident. The Taiwanese later (1952) operated the PB4Y-2 themselves.
http://www.taiwanairpower.org/history/shootdowns.html
Another Chinese B-24M, USAAF serial 44-42462, from the old Aircam series book "Consolidated B-24D-M Liberator".
Joe