Currently, I'm running on version 4.16. I tried with 4.15 as well but the problem still occurred.
Can you turn on verbose debug logging, rebuild your master list and pastebin or dropbox the log file so I can take a look at what's happening?
I looked through the logs myself and found the error messages related to building the master materials list. This comes up for pretty much every material it finds:
- [2017.06.19-22.36.45:617][ 14]LogMaterial:Warning: (Node TextureSampleParameter2D) Param2D> Requires Texture2D
- [2017.06.19-22.36.45:717][ 15]LogMaterial: Missing cached shader map for material BaseMaterial, compiling.
- [2017.06.19-22.36.45:718][ 15]LogMaterial:Warning: Failed to compile Material Instance /Game/SourceStuff/Materials/metal/metaltruss024a_mat.metaltruss024a_mat with Base BaseMaterial for platform PCD3D_SM5, Default Material will be used in game.
This happened with the sample base material provided in the sample materials zip as well.
If your base material has errors, check it, and try to fix whatever's wrong first.
UE straight up doesn't load materials that have "errors", as you can see from all the "Failed to compile Material Instance" warnings in the log.
Looks like it's looking for flat_normal in the content root, so you probably have to point the $bumpmap node to whatever directory you unpacked the sample material zip normal texture into, until the error message in the base material editor view is gone and it actually compiles. It'll probably take a while to actually compile all your other materials for the first time as well.
I have no idea what the HammUEr/road_street_04 and road_street_04_nrm it's looking for and can't find, I'm assuming those are yours you assigned to other nodes/used in your own base material and then moved/deleted?