Can’t extract symbol graph for `IndexStoreDB_LLVMSupport`

i am trying to generate the symbol graphs for the indexstore-db at swift-5.10-RELEASE, and am getting this error:

Couldn't load module 'IndexStoreDB_LLVMSupport' in the current SDK and search paths.
Current visible modules:
CDispatch
CFURLSessionInterface
CFXMLInterface
CIndexStoreDB
CoreFoundation
Cxx
CxxStdlib
Dispatch
DispatchIntrospection
Distributed
Foundation
FoundationNetworking
FoundationXML
Glibc
ISDBTestSupport
ISDBTibs
IndexStoreDB
IndexStoreDB_CIndexStoreDB
IndexStoreDB_Index
Observation
RegexBuilder
Swift
SwiftBridging
SwiftGlibc
SwiftOnoneSupport
SwiftOverlayShims
SwiftShims
XCTest
_Backtracing
_Builtin_intrinsics
_Builtin_stddef_max_align_t
_Concurrency
_Differentiation
_InternalStaticMirror
_InternalSwiftScan
_RegexParser
_StringProcessing
_SwiftConcurrencyShims
tibs

here is the invocation i am using:

swift symbolgraph-extract \
    -module-name IndexStoreDB_LLVMSupport \
    -target x86_64-unknown-linux-gnu \
    -minimum-access-level internal \
    -output-dir .testing/artifacts \
    -include-spi-symbols \
    -skip-inherited-docs \
    -emit-extension-block-symbols \
    -pretty-print \
    -I /swift/indexstore-db/.build.ssgc/debug \
    -I /swift/indexstore-db/lib/LLVMSupport/Support/Unix \
    -I /swift/indexstore-db/lib/LLVMSupport/Support/Windows \
    -I /swift/indexstore-db/lib/LLVMSupport/include \
    -I /swift/indexstore-db/lib/LLVMSupport/include/llvm-c \
    -I /swift/indexstore-db/lib/LLVMSupport/include/llvm/ADT \
    -I /swift/indexstore-db/lib/LLVMSupport/include/llvm/Config \
    -I /swift/indexstore-db/lib/LLVMSupport/include/llvm/Demangle \
    -I /swift/indexstore-db/lib/LLVMSupport/include/llvm/Support \
    -I /swift/indexstore-db/lib/Support \
    -I /swift/indexstore-db/lib/Support/include \
    -I /swift/indexstore-db/lib/Support/include/IndexStoreDB/Core \
    -I /swift/indexstore-db/lib/Support/include/IndexStoreDB/Database \
    -I /swift/indexstore-db/lib/Support/include/IndexStoreDB/Index \
    -I /swift/indexstore-db/lib/Support/include/IndexStoreDB/Support \
    -I /swift/indexstore-db/lib/Core/include \
    -I /swift/indexstore-db/lib/Core/include/IndexStoreDB/Core \
    -I /swift/indexstore-db/lib/Core/include/IndexStoreDB/Database \
    -I /swift/indexstore-db/lib/Core/include/IndexStoreDB/Index \
    -I /swift/indexstore-db/lib/Core/include/IndexStoreDB/Support \
    -I /swift/indexstore-db/lib/Database \
    -I /swift/indexstore-db/lib/Database/include \
    -I /swift/indexstore-db/lib/Database/include/IndexStoreDB/Core \
    -I /swift/indexstore-db/lib/Database/include/IndexStoreDB/Database \
    -I /swift/indexstore-db/lib/Database/include/IndexStoreDB/Index \
    -I /swift/indexstore-db/lib/Database/include/IndexStoreDB/Support \
    -I /swift/indexstore-db/lib/Database/lmdb \
    -I /swift/indexstore-db/lib/Index \
    -I /swift/indexstore-db/lib/Index/include/IndexStoreDB/Core \
    -I /swift/indexstore-db/lib/Index/include/IndexStoreDB/Database \
    -I /swift/indexstore-db/lib/Index/include/IndexStoreDB/Index \
    -I /swift/indexstore-db/lib/Index/include/IndexStoreDB/Support \
    -I /swift/indexstore-db/lib/Index/include/indexstore \
    -I /swift/indexstore-db/lib/CIndexStoreDB/include/CIndexStoreDB \
    -I /swift/indexstore-db/lib/CIndexStoreDB/include/IndexStoreDB/Core \
    -I /swift/indexstore-db/lib/CIndexStoreDB/include/IndexStoreDB/Database \
    -I /swift/indexstore-db/lib/CIndexStoreDB/include/IndexStoreDB/Index \
    -I /swift/indexstore-db/lib/CIndexStoreDB/include/IndexStoreDB/Support \
    -I /swift/indexstore-db/lib/CIndexStoreDB/include/indexstore \
    -I /swift/indexstore-db/Sources/ISDBTestSupport/INPUTS/CProject \
    -I /swift/indexstore-db/Sources/ISDBTestSupport/INPUTS/HermeticMixedLang \
    -I /swift/indexstore-db/Sources/ISDBTestSupport/INPUTS/HermeticMixedLangRelativePaths \
    -I /swift/indexstore-db/Sources/ISDBTestSupport/INPUTS/MainFiles \
    -I /swift/indexstore-db/Sources/ISDBTestSupport/INPUTS/MixedLangTarget \
    -I /usr/lib/swift \
    -I /usr/lib/swift/Blocks

what am i missing here?