If by "ambient on" you mean that everything is full bright - sounds like you skipped the LIGHT phase. Ok, you already tried other build methods, so that's actually improbable.
This batch file (which you'd have to adapt to your computer first) does a proper build with LIGHT. If all fails, maybe you want to try it:
"C:\Program Files\netradiant-20100214-win32\q3map2.exe" -fs_basepath "C:\Program Files\Tremulous" -fs_game "base" -custinfoparms -info -meta -patchmeta "C:\Program Files\Tremulous\base\maps\unnamed.map"
"C:\Program Files\netradiant-20100214-win32\q3map2.exe" -fs_basepath "C:\Program Files\Tremulous" -fs_game "base" -vis -saveprt "C:\Program Files\Tremulous\base\maps\unnamed.map"
"C:\Program Files\netradiant-20100214-win32\q3map2.exe" -fs_basepath "C:\Program Files\Tremulous" -fs_game "base" -light -bouncegrid -custinfoparms -filter -patchshadows "C:\Program Files\Tremulous\base\maps\unnamed.map"
"C:\Program Files\Tremulous\tremulous.exe" +set fs_basepath "C:\Program Files\Tremulous" +set fs_game base +devmap "unnamed"