order of materials changes on reimport

I have strange problem. In my 3ds max asset creation workflow i use 1 dummy box as a master parent with all the geometry pieces and UCX meshes are linked to it.
This helps to maintain pivot of the asset even after serious changes of the asset’s dimension and so on. Since upgrading to 4.14 i am frequently running into serious issue.

Depending on what meshes containg what material IDs are in the exportet asset, material ID swaps after reimport.

Let’s say i have asset made from multiple meshes and i import it into UE. I assing materials to the IDs and all is fine. However, if merge some geometry in 3ds max and then reimport, materials get randomly swapped.
To illustrate my point i made few screenshots:

This si my 3ds max scene. Both assets have same name and are essentially same. Except the left one has all the geometry merged together, right one is composed of multiple meshes. They both have same material with submaterial named 1,2,3,4.

If i export left (merged together) one, asset in UE looks as it should, all materials are in correct places.

If i export right one where multiple meshes are linked to export node, asset in UE looks differently. Notice how materials slots in the editor stay same but slots in the asset LOD0 section changes for no apparent reasons. (bottom right corner of the image.)

Another example could be changing small detail on asset and reimporting it again. It leads in to another random change.

I cannot find mention about this problem on the internet so it’s possible I am doing something wrong. Help please.
Thank you, H.