Material Function Instances - Texture Parameter bug??

I am wondering if there is a known issue with Parameters of Material Function Instances? I have set up one main Material Function as a master, this material function deals with the distance blending, I have then converted all the textures within the master Material Function as Parameters, to be used in Material Function Instances, so I can easily have one for grass, gravel, rock etc, which I will then call upon within my Master Material, to be used in my landscape.

The problem is, when I change the textues in the Material Function Instance (MFI) window (screen below), the textures do not update correctly in the preview or in the Master Material when applied to the landscape, or even in a node preview of the MFI in the master material blue print. It also seems to be temperamental; sometimes it will preview as a grass texture, used in another MFI, sometimes it will preview the default MF texture, and once it even previewed the correct texture! - which is why I think it is a bug. See screens below.

Any info would be apprecieted.
(I can do what i need to by just using Materials Functions, but it kind of negates the whole point of having Material Function Instances in the first place).

I’m having a similar issue also - very similar circumstance - Had some nodes ive rebuilt into a function, plug everything in - where the nodes before worked perfectly, I now have a black result -

Not sure I’m mine is a error on the material function itself

(BTW I’m receiving no errors in engine, but I’m assuming the material function maybe broken/erroring)

OR if its to do with the material instance I’m passing it through too,

so +1