How to reproduce:
1. Open uploaded "ExportFBXBug" project
2. Open SampleScene
3. Right-click on "ProblemFBX" GameObject in the hierarchy
4. Choose Export to FBX
5. Set Export Path to any except Assets folder
6. Export

Expected result: FBX Exports
Actual result: Unity Crashes

Reproducible with: 4.0.1 (2019.4.31f1, 2020.3.21f1, 2021.1.26f1), 4.1.0 (2019.4.31f1, 2020.3.21f1, 2021.1.26f1), 4.1.1 (2019.4.31f1, 2020.3.21f1, 2021.1.26f1, 2021.2.0b16, 2022.1.0a12)

Note: Selecting "Core" Mesh after expanding the "ProblemFBX" file in the project also crashes Unity (might be related to this crash)

Stack Trace:

0x00007ffdf784e798 (UnityFbxSdkNative) SWIGRegisterStringCallback_Globals
0x00007ffdf78477ea (UnityFbxSdkNative) SWIGRegisterStringCallback_Globals
0x00007ffdf77b490d (UnityFbxSdkNative) CSharp_AutodeskfFbx_FbxLayerElementArray_Add__SWIG_4___
0x000002647544b2e6 (Mono JIT Code) (wrapper managed-to-native) Autodesk.Fbx.NativeMethods:FbxLayerElementArray_Add__SWIG_4 (System.Runtime.InteropServices.HandleRef,Autodesk.Fbx.FbxVector4)
0x000002647544b01b (Mono JIT Code) \[FbxLayerElementArray.cs:77] Autodesk.Fbx.FbxLayerElementArray:Add (Autodesk.Fbx.FbxVector4)