"Where are you? I cannot see you."
Translation:Hol vagy? Nem látlak.
This is obviously making it a much more complicated sentence than it needs to be, but is there anything actually wrong with "Hol vagytok? Nem tudlak látni"? Can "tud" actually be used this way? Just curious.
"Where are you?" can be translated either as "Hol vagy?" (singular) or "Hol vagytok?" (plural). "Nem tudlak látni" sounds strange. The short format "Nem látlak" indirectly refers to 'missing capability' of seeing. If you want to further emphasise this capability element you might say "Képtelen vagyok látni téged" - "I am not capable seeing you".
Tud is rarely used with látni. At most when a strong emphasis is needed, or if lát is used figuratively, but even then it's not necessary to add tud.