There are generally two types of bugs for obex-data-server:
To get proper backtraces and ods debug output, you need to rebuild ods with debug information:
./configure --enable-debug
To get backtrace when crash happens, run ods with gdb
gdb obex-data-server (gdb) run -nd
And after the crash happens:
(gdb) bt
To get ods debug output, run obex-data-server manually (you might have to kill the one, that's already running):
killall obex-data-server ./obex-data-server --no-daemon