Adding a connected bones to an anim curve crash UE4.21

Hi,

Everytime I try to add connected bones to an Anim Curve the engine crash.

How to reproduce:
Open a skeletal mesh → Anim Curve window → add a curve → details panel → click ‘+’ to add Connected Bones => Crash

Log:
[2019.03.15-15.15.54:435][507]LogStats: FPlatformStackWalk::StackWalkAndDump - 0.300 s
[2019.03.15-15.15.54:435][507]LogOutputDevice: Error: === Handled ensure: ===
[2019.03.15-15.15.54:435][507]LogOutputDevice: Error:
[2019.03.15-15.15.54:435][507]LogOutputDevice: Error: Ensure condition failed: BoneReference.bUseSkeletonIndex [File:D:\Build++UE4\Sync\Engine\Source\Runtime\Engine\Private\BoneContainer.cpp] [Line: 261]
[2019.03.15-15.15.54:435][507]LogOutputDevice: Error:
[2019.03.15-15.15.54:435][507]LogOutputDevice: Error: Stack:
[2019.03.15-15.15.54:435][507]LogOutputDevice: Error: [Callstack] 0x00007ffad22ea5ca UE4Editor-Engine.dll!UnknownFunction []
[…]

[2019.03.15-15.15.55:231][507]LogWindows: Windows GetLastError: L’opération a réussi. (0)
[2019.03.15-15.15.55:935][507]LogWindows: Error: === Critical error: ===
[2019.03.15-15.15.55:935][507]LogWindows: Error:
[2019.03.15-15.15.55:935][507]LogWindows: Error: Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\Build++UE4\Sync\Engine\Source\Runtime\Core\Public\Containers/Array.h] [Line: 611]
[2019.03.15-15.15.55:935][507]LogWindows: Error: Array index out of bounds: -1 from an array of size 16
[2019.03.15-15.15.55:935][507]LogWindows: Error:
[2019.03.15-15.15.55:935][507]LogWindows: Error: [Callstack] 0x00007ffb2c50a388 KERNELBASE.dll!UnknownFunction []
[…]

OS windows 10

Hello,

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Thanks