When I use the Ectoplasm on the Item Drain, it doesn’t show the Ectoplasm at all, and when the Ectoplasm goes into the Fluid Tank, it's upside-down instead of the bottom. Only the Fluid Pipe and Spout are working perfectly.

I'll look into it

Create issue. They've fixed it in dev: Creators-of-Create/Create#7236

I find it strange how ectoplasm is being treated like a isLighterThanAir fluid when the value isn't even specified in the FluidType

    public static final RegistryObject<FluidType> ECTOPLASM_TYPE = FLUID_TYPES.register("ectoplasm", () ->
        new EctoplasmFluidType(FluidType.Properties.create().lightLevel(7).density(0).viscosity(0)
                .canPushEntity(false).canSwim(false).canConvertToSource(true).canDrown(false)
                .pathType(BlockPathTypes.WATER).supportsBoating(false).temperature(-196)
                .canExtinguish(false).adjacentPathType(BlockPathTypes.DANGER_OTHER)
                .canHydrate(false)));

isLighterThanAir is not a value directly specified. It's derived from density:
https://github.com/MinecraftForge/MinecraftForge/blob/d7363005668998b8e81dc8787f2204b48a4c5ea9/src/main/java/net/minecraftforge/fluids/FluidType.java#L820-L823

that's interesting, I'll fix that in the next patch

Fixed