Is Groom broken in 5.4?

I have been using an alembic groom successfully on a bird model in 5.3. After updating to 5.4 the same groom turns into a strange rasterized abomination as soon as I hit the simulate button. Check out the screenshots. The first two show the expected behaviour in UE 5.3, the last two the broken behaviour in 5.4 using the same groom and model. Can anybody explain this strange behaviour to me?