I have the same issue appearing on 5.0.3.
The same project (cloned from a git repository) works on other PCs. Another project, namely the First Person Template, works on my PC with UE503. I removed and re-installed UE503, and the newest NVIDA driver, and ensured Windows 10 updates are installed. The only obvious difference is hardware. My PC uses HDD, while other PCs have SSDs.
Below is the stack trace.
Assertion failed: !bCompressionInProgress [File:D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Animation\AnimSequence.cpp] [Line: 2124]
UnrealEditor_Engine!UAnimSequence::RequestAnimCompression() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Animation\AnimSequence.cpp:2124]
UnrealEditor_Engine!UAnimSequence::PostLoad() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Animation\AnimSequence.cpp:926]
UnrealEditor_CoreUObject!UObject::ConditionalPostLoad() [D:\build\++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\Obj.cpp:1103]
UnrealEditor_CoreUObject!EndLoad() [D:\build\++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:1701]
UnrealEditor_CoreUObject!<lambda_c8710bcd35c9e247c18bb173ed0f9483>::operator()() [D:\build\++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:1264]
UnrealEditor_CoreUObject!LoadPackageInternal() [D:\build\++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:1366]
UnrealEditor_CoreUObject!LoadPackage() [D:\build\++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:1520]
UnrealEditor_CoreUObject!LoadPackage() [D:\build\++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:1500]
UnrealEditor_UnrealEd!UEditorEngine::Map_Load() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\EditorServer.cpp:2694]
UnrealEditor_UnrealEd!UEditorEngine::HandleMapCommand() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\EditorServer.cpp:6232]
UnrealEditor_UnrealEd!UEditorEngine::Exec() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\EditorServer.cpp:5722]
UnrealEditor_UnrealEd!UUnrealEdEngine::Exec() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\UnrealEdSrv.cpp:659]
UnrealEditor_UnrealEd!FEditorFileUtils::LoadMap() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\FileHelpers.cpp:2761]
UnrealEditor_UnrealEd!FEditorFileUtils::LoadDefaultMapAtStartup() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\FileHelpers.cpp:4336]
UnrealEditor_UnrealEd!FUnrealEdMisc::OnInit() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\UnrealEdMisc.cpp:359]
UnrealEditor_UnrealEd!EditorInit() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\UnrealEdGlobals.cpp:134]
UnrealEditor!GuardedMain() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Launch.cpp:159]
UnrealEditor!GuardedMainWrapper() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:147]
UnrealEditor!LaunchWindowsStartup() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:283]
UnrealEditor!WinMain() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:330]
UnrealEditor!__scrt_common_main_seh() [d:\a01\_work\6\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]
kernel32