A regression was introduced in Titanium SDK 5.4.0 with detecting the Android NDK on Windows. When Android NDK 11 came out, it no longer included RELEASE.txt which we relied on to determine if the folder contained a valid NDK. Thus Titanium could not find the NDK 11 install.
TIMOB-20613 "improved" Android NDK detection by searching for specific files and directories within the NDK directory to validate it was indeed an NDK. However, there's a typo by which it searches for ndk-gdb.cmd instead of ndk-gdb-py.cmd on Windows.