So, what can I do to fix this? I tried re-downloading Indistinguishable Billboards and installing it new. This did not work unfortunately.
I also tried using the Vanilla Skyrim LOD Billboards from TES5LODGen before, this did not work either though and produced the same error.
This is a screenshot of part of the file system of Indistinguishable Billdboards: https://i.imgur.com/2BeSvlb.png
It shows the treeaspen01_0006a9e6.dds or am I being mistaken?
You need to make sure the files are available at the correct location and accessible by the program. It is a very simple file check. It fails for outside reasons.
The screenshot shows the mod folder. Not the if the mod is enabled and if the files are available at the (virtual) data folder. Use MOs right window Data tab.
Also pay attention to the installation instructions of DynDOLOD:
From the DynDOLOD Standalone archive copy the content of the 'DynDOLOD' folder, which contains the files DynDOLOD.exe, TexGen.exe, DynDOLOD_QuickStart.html and the sub folders 'Docs' and 'Edit Scripts' with all their content into a new 'DynDOLOD' folder outside of special OS folders like 'Programs Files' or 'Program Files (x86)', the SteamApps or game folders and Mod Organizers virtual file structure. Do not mix with old versions or xEdit installation.