Engine Version: 4.1.1
When following the material tutorial, I’m unable to set the color for the material instance dynamic by clicking the Set Vector Parameter Value node Value, choosing a color in the color picker and click OK button, it does not set the color, save the color setting, or display the color. However, in order to set the color to make it work as a workaround, I have to create a Make LinearColor node and manually set the values for R,G,B there, and then it works.
Following this Material Tutorial:
Attachment List: First picture shows the problem. Second shows a manual blueprint connection workaround.