yes, the invisipokébug is back in the safari, but with a little patience you can fix it yourself
only the pokémon (and trainers, their poké, basically anything that isn't part of the landscape) that are present when you enter are invisible
invisible pokémon can be fainted, and anything that appears after you're already in the affected tile will be visible to you while you're still there
(if you leave and reenter, anything that was visible becomes invisible again, since it was present when you entered the second time)
only the pokémon (and trainers, their poké, basically anything that isn't part of the landscape) that are present when you enter are invisible
invisible pokémon can be fainted, and anything that appears after you're already in the affected tile will be visible to you while you're still there
(if you leave and reenter, anything that was visible becomes invisible again, since it was present when you entered the second time)