You may want to triple check those rooms a leak showed in the logs.
Ensure that you have at least one env_cubemap entity in any room, dosen't matter where just place on in a room.
Code:
materialPath: C:\Program Files (x86)\Steam\steamapps\common\left 4 dead 2\left4dead2\materials
Loading C:\Program Files (x86)\Steam\steamapps\common\left 4 dead 2\sdk_content\mapsrc\TEST MAP A\room 1a.vmf
fixing up env_cubemap materials on brush sides...
0...1...2...3...4...5...6...7...8...9...10**** leaked ****
Entity info_landmark (-1382.98 1322.00 20.00) leaked!
You want to also check any models your using, are the correct ones. My guess would be that hammer dosen't like that model. Try deleting it from the map.
Code:
DataLinker total stream size 0.0 KiB
Error! To use model "models/props_fairgrounds/alligator.mdl"
with prop_static, it must be compiled with $staticprop!
Error loading studio model "models/props_fairgrounds/alligator.mdl"!
Also you might want to remove that red line that goes no-where, unsure what that is.