Disable all visgroups except for displacements and check them, though if I were you I would straight up destroy all existing displacements and do them again from scratch.
I did notice this in your compile log error report:
Have a look at that, however this should not cause the compile to fail at all.
god no; so many hours with displacements i'd die If I had to redo them. I ran with only displacments on and vbsp just crashes.
here is the log
** Executing...
** Command: "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\bin\vbsp.exe"
** Parameters: -game "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\tf" "C:\HammerAutosave\koth_outland_a14.vmf"
Valve Software - vbsp.exe (Dec 7 2014)
4 threads
materialPath: C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\tf\materials
Loading C:\HammerAutosave\koth_outland_a14.vmf
Patching WVT material: maps/koth_outland_a14/moon/blend_moon_dust_moon_craters3_wvt_patch
Patching WVT material: maps/koth_outland_a14/moon/blend_moon_dust_moon_craters2_wvt_patch
Patching WVT material: maps/koth_outland_a14/moon/blend_moon_dust_moon_craters_wvt_patch
fixing up env_cubemap materials on brush sides...
*** Error: Skybox vtf files for skybox/sky_nightfall_01 weren't compiled with the same size texture and/or same flags!
Can't load skybox file skybox/sky_nightfall_01 to build the default cubemap!
*** Error: Skybox vtf files for skybox/sky_nightfall_01 weren't compiled with the same size texture and/or same flags!
Can't load skybox file skybox/sky_nightfall_01 to build the default cubemap!
Finding displacement neighbors...
Found a displacement edge abutting multiple other edges.
** Executing...
** Command: "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\bin\vvis.exe"
** Parameters: -game "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\tf" -fast "C:\HammerAutosave\koth_outland_a14"
Valve Software - vvis.exe (Dec 7 2014)
fastvis = true
4 threads
reading c:\hammerautosave\koth_outland_a14.bsp
Error opening c:\hammerautosave\koth_outland_a14.bsp
** Executing...
** Command: "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\bin\vrad.exe"
** Parameters: -game "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\tf" -noextra "C:\HammerAutosave\koth_outland_a14"
Valve Software - vrad.exe SSE (Dec 7 2014)
Valve Radiosity Simulator
4 threads
[Reading texlights from 'lights.rad']
[37 texlights parsed from 'lights.rad']
Loading c:\hammerautosave\koth_outland_a14.bsp
Error opening c:\hammerautosave\koth_outland_a14.bsp
** Executing...
** Command: Copy File
** Parameters: "C:\HammerAutosave\koth_outland_a14.bsp" "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\tf\maps\koth_outland_a14.bsp"
The command failed. Windows reported the error:
"The system cannot find the file specified."