After attempting to import any mesh, even a simple box from Max to UE4 using FBX or OBJ, 4.6.1 crashes out and leaves me with an error report. First time I’ve ever had this issue - need to figure out a fix for this - an Environment Artist who can’t import his models makes his trade very… difficult 
MachineId:B71D1292442E381DC562CC9093C2FAFC
EpicAccountId:
Unknown exception - code 00000001 (first/second chance not available)
Assertion failed: ChartB.Join[ Side ^ 1 ] == i [File:D:\BuildFarm\buildmachine_++depot+UE4-Releases+4.6\Engine\Source\Developer\MeshUtilities\Private\LayoutUV.cpp] [Line: 374]
KERNELBASE + 42141 bytes
UE4Editor_Core + 3092349 bytes
UE4Editor_Core + 1597688 bytes
UE4Editor_Core + 1479058 bytes
UE4Editor_MeshUtilities + 222402 bytes
UE4Editor_MeshUtilities + 149371 bytes
UE4Editor_Engine + 8442069 bytes
UE4Editor_Engine + 8443260 bytes
UE4Editor_Engine + 8423259 bytes
UE4Editor_UnrealEd + 9575680 bytes
UE4Editor_UnrealEd + 9136826 bytes
UE4Editor_UnrealEd + 9270727 bytes
UE4Editor_AssetTools + 847862 bytes
UE4Editor_AssetTools + 841823 bytes
UE4Editor_ContentBrowser + 1614625 bytes
UE4Editor_ContentBrowser + 87303 bytes
UE4Editor_ContentBrowser + 121209 bytes
UE4Editor_ContentBrowser + 1344569 bytes
UE4Editor_Slate + 2116506 bytes
UE4Editor_Slate + 2296435 bytes
UE4Editor_Slate + 432060 bytes
UE4Editor_Slate + 160583 bytes
UE4Editor_Slate + 832224 bytes
UE4Editor_Slate + 770598 bytes
UE4Editor_Core + 2484713 bytes
UE4Editor_Core + 2400763 bytes
UE4Editor_Core + 2489275 bytes
UE4Editor_Core + 2387186 bytes
user32 + 105425 bytes
user32 + 104666 bytes
UE4Editor_Core + 2490486 bytes
UE4Editor!FEngineLoop::Tick() + 3434 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.6\engine\source\runtime\launch\private\launchengineloop.cpp:2193]
UE4Editor!GuardedMain() + 479 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.6\engine\source\runtime\launch\private\launch.cpp:131]
UE4Editor!GuardedMainWrapper() + 26 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.6\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() + 249 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.6\engine\source\runtime\launch\private\windows\launchwindows.cpp:202]
UE4Editor!__tmainCRTStartup() + 329 bytes [f:\dd\vctools\crt\crtw32\dllstuff\crtexe.c:618]
