shift in dates using complete on data.table

Why is the complete function shifting index by 1 hour?

library(xts)
library(tidyr)
x = seq.Date(from = as.Date('2012-03-10'), to = as.Date('2012-03-25'), by = 'week')
x = xts::xts(1:length(x), order.by = as.POSIXct(paste0(x, ' 00:00:00')))
x = dat.tale::as.data.table(x)

x %>% 
      tidyr::complete(index = seq(min(index), max(index), 'day')) %>% 
      data.frame()

This gives an NA value for 2012-03-17 that should have a value of 2 because the index column as been shifted by one hour. For other months this type of logic works fine. Running this for July, for example, gives the expected result.

How can I edit this so the date shift does not happen?