UE5 Crash On Load - Parameter LFO automation with another LFO


I have an event for characters speaking and want to randomize it so the person speaking changes at varied intervals, and then use a parameter to control the random rate in-engine.

My implementation for this is as so…

  1. The voices are triggered as multi-instruments in a labeled parameter sheet “VOXSwitch” (so I can use AHDSR to fade them out when they switch).
  2. VOXSwitch is modulated with a LFO to switch between voices.
  3. The rate of that LFO is automated by param “Random” using a random ramp LFO.
  4. The Random LFO rate/direction is automated with a continuous param “VOXRate” to change the random rate via in-engine parameters.

It works fine in Studio, but after building banks and opening UE5 it crashes. The final error in the UE crash log is…

Error: c:\jk\workspace\Build__2.2__Unreal_Win\studio_api\src\fmod_model_base.h(38) - assertion: ‘mMagic == MAGIC_WORD’ failed

It also causes Studio to crash after closing Studio.

I tested this issue a few times and the cause always seems to be when you automate a parameter LFO with another parameter using LFO modulation, regardless of seek speed.

Software versions tested:
FMOD 2.02.08
FMOD 2.02.09
Unreal Engine 5.0.3


Is it possible to upload your FMOD project to your profile to test on my end?