Please provide a reproducible example of the problem. The following code tries to do something like what I think you've done and it works.
library(tsibble)
library(feasts)
library(ggplot2)
set.seed(3)
iniciativa <- tibble(
tipo_demanda = rep(c("A","B"), 10),
data_planejada = sample(seq(as.Date("2020-01-01"), length=20, by="1 day"), size=20),
value = sample(seq(100), size=20)
)
iniciativa_tsbl <- as_tsibble(iniciativa,
key = c(tipo_demanda),
index = data_planejada
) %>%
fill_gaps(.full = TRUE)
iniciativa_tsbl %>%
autoplot(value) +
geom_point()
#> Warning: Removed 2 row(s) containing missing values (geom_path).
#> Warning: Removed 20 rows containing missing values (geom_point).

Created on 2020-11-04 by the reprex package (v0.3.0)