Editor and Package crash when playing a level sequence


I’m becoming crazy about a crash sequence : when I play a level sequence, my editor crash :

Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\Build++UE4\Sync\Engine\Source\Runtime\Core\Public\Containers/Array.h] [Line: 611]
Array index out of bounds: 0 from an array of size 0

0x00007ffec7d84b59 KERNELBASE.dll!UnknownFunction []
0x00007ffe5f5b1f37 UE4Editor-Core.dll!UnknownFunction []

I have passed hours trying to understand and testing but… nothing works.

I have completely rebuilt my animation and testing after every track adds. At a moment, the editor crash, I remove the last track, but the sequence continues to crash every time I run the editor…

Strange fact : if a play the sequence with begin play of the BP everything works fine, but with an event not (a simple keyboard event…)

Somebody has an idea ?

Thanks for your time !