Autopltoing a dataset that has been converted to TS

I have a dataset named "BEDATA_grouped" that I am trying to autoplot. However, whenever I attempt to convert into a time series and use the autoplot function, I get the following error:

Error in `ggplot2::autoplot()`:
! Objects of type tbl_df/tbl/data.frame not supported by autoplot.
Run `rlang::last_error()` to see where the error occurred.

To convert it to a time series I did the following :

BEDATA_GROUPED %>% mutate(occurrence_yrmn = yearmonth(occurrence_yrmn)) %>% as_tsibble(index = occurrence_yrmn)

Weirdly enough, when I use the following, I am able to use the autoplot function:

BEDATA_GROUPEDts <- ts(BEDATA_GROUPED[,2], frequency = 12, start = c(2014, 1))

I'm wondering why one allows me to autoplot whilst the other does not. The first way is referenced in https://otexts.com/fpp3/tsibbles.html#:~:text=This%20can%20be%20converted%20to%20a%20tsibble%20object%20using%20the%20following%20code%3A.

Dataset:

structure(list(occurrence_yrmn = c("2014-January", "2014-February", 
"2014-March", "2014-April", "2014-May", "2014-June", "2014-July", 
开发者_如何学JAVA"2014-August", "2014-September", "2014-October", "2014-November", 
"2014-December", "2015-January", "2015-February", "2015-March", 
"2015-April", "2015-May", "2015-June", "2015-July", "2015-August", 
"2015-September", "2015-October", "2015-November", "2015-December", 
"2016-January", "2016-February", "2016-March", "2016-April", 
"2016-May", "2016-June", "2016-July", "2016-August", "2016-September", 
"2016-October", "2016-November", "2016-December", "2017-January", 
"2017-February", "2017-March", "2017-April", "2017-May", "2017-June", 
"2017-July", "2017-August", "2017-September", "2017-October", 
"2017-November", "2017-December", "2018-January", "2018-February", 
"2018-March", "2018-April", "2018-May", "2018-June", "2018-July", 
"2018-August", "2018-September", "2018-October", "2018-November", 
"2018-December", "2019-January", "2019-February", "2019-March", 
"2019-April", "2019-May", "2019-June", "2019-July", "2019-August", 
"2019-September", "2019-October", "2019-November", "2019-December", 
"2020-January", "2020-February", "2020-March", "2020-April", 
"2020-May", "2020-June", "2020-July", "2020-August", "2020-September", 
"2020-October", "2020-November", "2020-December", "2021-January", 
"2021-February", "2021-March", "2021-April", "2021-May", "2021-June", 
"2021-July", "2021-August", "2021-September", "2021-October", 
"2021-November", "2021-December"), MCI = c(586, 482, 567, 626, 
625, 610, 576, 634, 636, 663, 657, 556, 513, 415, 510, 542, 549, 
618, 623, 666, 641, 632, 593, 617, 541, 523, 504, 536, 498, 552, 
522, 519, 496, 541, 602, 570, 571, 492, 560, 525, 507, 523, 593, 
623, 578, 657, 683, 588, 664, 582, 619, 512, 630, 644, 563, 654, 
635, 732, 639, 748, 719, 567, 607, 746, 739, 686, 805, 762, 696, 
777, 755, 675, 704, 617, 732, 609, 464, 487, 565, 609, 513, 533, 
505, 578, 526, 418, 428, 421, 502, 452, 509, 492, 478, 469, 457, 
457)), class = c("tbl_df", "tbl", "data.frame"), row.names = c(NA, 
-96L))