Is it a bug for the function ifelse?

Here is my vector:

x <- c("a", "b", "c")

I am going to extract only the odd elements from the vector so I write something like this:

ifelse(length(x) > 0, x[seq(from = 1, to = length(x), by = 2)], NA)

But the result returned is just only"a". However, if I check the condition and run the TRUE statement separately, I got different results.

length(x) > 0   #TRUE
x[seq(from = 1, to = length(x), by = 2)]   # "a" "c"

Does anyone know why? Thank you!