A strange behavior of the mvrnorm() function occured to me as I tried to make some calculation in one of the arguments.

This does do the job:

mvrnorm(
  n=200,
  mu = c('x'=0,'y'=0), 
  Sigma = matrix(c(1,0.5,0.5,1),nrow = 2), 
  empirical = TRUE)

Yet, replacing n = 200 with n = (1-0.8)*1000, does NOT do the job:

mvrnorm(
  n=(1-0.8)*1000,
  mu = c('x'=0,'y'=0), 
  Sigma = matrix(c(1,0.5,0.5,1),nrow = 2), 
  empirical = TRUE)

Error in eS$vectors %*% diag(sqrt(pmax(ev, 0)), p) %*% t(X) : 
  non-conformable arguments
In addition: Warning message:
In matrix(rnorm(p * n), n) :
  data length [399] is not a sub-multiple or multiple of the number of rows [199]

Why is this hapening?