Not sure if it's something you'd even want to support, but it's a thing. This is with vanilla pistons, which don't move the blocks in question at all without quark installed. I was attempting to move a multi block structure with vanilla-style flying machines. (I tried with and without them actually rotating.) This doesn't happen every time, but seems to increase with larger structures. Real bummer for the slimestone/create quarry I was working on, but I completely understand if that sort of thing was never intended.

Game crashes with error "Pose stack not empty."

crash-2020-07-15_19.16.36-client.txt

crash-2021-01-18_18.26.44-client.txt

Same issue. Don't know what mod caused it this time. We had it once before with vertical slabs ( DoubleSlabs-1.16-3.4.10.jar ) but I don't have that particular log anymore.

The server doesn't crash, just client side. It would be nice if somehow you could remove unsupported blocks from anything that moves using create instead of crashing the game.

The previous comment was because of double slabs mod!

[20Jan2021 22:11:35.799] [Render thread/WARN] [net.minecraft.client.network.play.ClientPlayNetHandler/]: Received passengers for unknown entity
[20Jan2021 22:11:37.503] [Render thread/ERROR] [com.simibubi.create.Create/]: TileEntity doubleslabs:dynamic_slab didn't want to render while moved.

[20Jan2021 22:11:37.551] [Render thread/FATAL] [net.minecraftforge.common.ForgeMod/]: Preparing crash report with UUID 0d17c8b0-a272-4cf3-8bff-a7e5061dd49d
[20Jan2021 22:11:37.556] [Render thread/FATAL] [net.minecraft.client.Minecraft/]: Unreported exception thrown!
java.lang.IllegalStateException: Pose stack not empty

Edit:
With explain render set to true

[20Jan2021 23:17:32.337] [Render thread/ERROR] [com.simibubi.create.Create/]: TileEntity doubleslabs:dynamic_slab didn't want to render while moved.

java.lang.NullPointerException: null
at cjminecraft.doubleslabs.client.render.SlabTileEntityRenderer.render(SlabTileEntityRenderer.java:33) ~[?:3.4.10]
at cjminecraft.doubleslabs.client.render.SlabTileEntityRenderer.func_225616_a_(SlabTileEntityRenderer.java:18) ~[?:3.4.10]
at com.simibubi.create.foundation.utility.TileEntityRenderHelper.renderTileEntities(TileEntityRenderHelper.java:47) [?:mc1.16.3_v0.3e]
at com.simibubi.create.content.contraptions.components.structureMovement.ContraptionRenderer.renderTileEntities(ContraptionRenderer.java:74) [?:mc1.16.3_v0.3e]
at com.simibubi.create.content.contraptions.components.structureMovement.ContraptionRenderer.render(ContraptionRenderer.java:46) [?:mc1.16.3_v0.3e]
at com.simibubi.create.content.contraptions.components.structureMovement.AbstractContraptionEntityRenderer.render(AbstractContraptionEntityRenderer.java:51) [?:mc1.16.3_v0.3e]
at com.simibubi.create.content.contraptions.components.structureMovement.AbstractContraptionEntityRenderer.func_225623_a_(AbstractContraptionEntityRenderer.java:13) [?:mc1.16.3_v0.3e]

I solved it by just throwing try catch around
renderer.render(tileEntity, pt, ms, buffer, WorldRenderer.getLightmapCoordinates(world, lightPos), OverlayTexture.DEFAULT_UV);

I'm sure you guys have way better solution to this however.

I would rather have this then crashing the client.

Issue should now be fixed by d249318 in 0.3.1c