I don't know PitBull so I'm not sure what Status() or Angle() is doing but my best guess is that it has more than 1 return and all but the first one are being cut off because it's no longer the last return in the format.
Without thinking too hard, maybe something like still treating the return as two strings:
Lua Code:
local s = Status(unit)
if s then
return s
end
local r,g,b = ClassColor(unit)
local string1 = string.format('|cff%02x%02x%02x%s|r %s%s%s|', r,g,b,Name(unit),Angle(AFK(unit) or DND(unit)))
local cur,max = HP(unit),MaxHP(unit);
local hr,hg,hb=HPColor(cur,max);
return string1 .. "|cff%02x%02x%02x%.0f|r" or "", hr,hg,hb,100*cur/max