Material functions get disconnected

I’ve imported a large 3dsmax file using Unreal Studio ( 4.19 ). That import also created the materials. But some materials that have material functions keep getting disconnected without any reason. There’s no errors and when I reconnect the function to the material, all is fine. But after light baking or re-opening the project, they’re disconnected again. As there are over 700 materials created with the import, I can imagine this could be a memory issue, but there’s no error message.

Here’s an example:


Is there an explanation why this happens? Do I have to change a memory setting somewhere in an ini for the engine?

I hope someone can help.