Alembic import crashes UE instantly. C4D to Unreal

Development Pipeline & Plugins
1

Hello everybody,

by now I read through at least 15 different threads where people reort to have the same problem that I have:

Alembic import.

When I import my alembic file (geometry cache), that was created by Cinema4D 2024 or 2025, after I made my import settings and hit import the engine instantly crashes. Every single time.

I did check the following things:
My C4D scene is all quads, meaning no n-gons or tris at all.
The alembic file is 1,44 gb which is not very much for a geometry cache.
I also tried the c4d datasmith import, which also failed and I presume the reason is the same. I presume that c4d internally saves the cineware data as alembic, the behaviour of the engine is absolutely the same.
I tried importing an alembic with a cube that has 6 polygons - no problem.

Here’s some stats abount my rig:
UE 5.5.1
Windows 10 with latest updates, latest nVidia drivers, latest Mainboard Bios
RTX4080 Super and an RTX 3080 installed
128 gigs of Ram
All SSD
No network drives, no VPNs no nothing, everything superfast and stable
Monitors are 5K Ultrawide and 2,5k 16:9 via HDMI and DP

People are complaining abount this issue since 7 or 8 years at least and still it is not really possible to rely on the alembic import.

Is there anything that I am missing?

Here’s the log:
LoginId:bfe810b244aa844508add28fe3fe0a02
EpicAccountId:43ad4cec41074764b8c511b6c4db9433

Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\build++UE5\Sync\Engine\Source\Runtime\Core\Public\Containers\Array.h] [Line: 783]
Array index out of bounds: 712363 into an array of size 712363

UnrealEditor_AlembicLibrary
UnrealEditor_AlembicLibrary
UnrealEditor_AlembicLibrary
UnrealEditor_AlembicLibrary
UnrealEditor_AlembicLibrary
UnrealEditor_AlembicLibrary
UnrealEditor_AlembicLibrary
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
kernel32
ntdll

The strange thing about the log is the path:
D:\build++UE5\Sync\Engine\Source\Runtime\Core\Public\Containers\

this does not exist on my pc, is that something from development?

In case anybody wants to try, here is the alembic cache:

https://www.dropbox.com/scl/fi/v7ur3tbz3g320yvkyleep/SonnenblumeRigV05.abc?rlkey=0wklqok0gy8yep8phggdbklxs&dl=0

What can I do, is there any alternatives? I tried FBX but that messes up my whole MoGraph setup and is totally unusable.

Any help is highly appreciated!
Cheers

2

I also tried the alembic streaming method by activating the second alembic experimental plugin. When it’S activated you can place the “abc streaming actor” with the place actors panel and stream the abc file from your harddisk to unreal without importing it. it also crashes the program.