ggplotly() is not displaying the tooltip with option hoveron="fills"

The hover text / tooltip is not being displayed:

library(ggplot2)
library(plotly)
library(sf)

nc <- st_read(system.file("shape/nc.shp", package="sf")) %>% 
         dplyr::mutate('BIR74_intervals'=cut(BIR74,breaks=6,dig.lab=5))

map <- ggplot() + geom_sf(data=nc,
  aes(fill=BIR74_intervals, text=paste0("Name: ", NAME, "\n",BIR79)))

map %>% ggplotly(tooltip=c("text")) %>% style(hoveron='fills') 

However, if %>% style(hoveron='fills') is removed, then the tooltip appears.

Moreover, if text is set to just text=paste0("Name: ", NAME), the tooltip is displayed but in a wrong way.

Thanks in advance.

> sessionInfo()

R version 3.6.1 (2019-07-05)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 18363)

Matrix products: default

locale:
[1] LC_COLLATE=English_United States.1252 
[2] LC_CTYPE=English_United States.1252   
[3] LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C                          
[5] LC_TIME=English_United States.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods  
[7] base     

other attached packages:
[1] sf_0.9-3       plotly_4.9.2.1 ggplot2_3.3.0  h2o_3.30.0.1  

loaded via a namespace (and not attached):
 [1] tidyselect_1.0.0    xfun_0.13           purrr_0.3.4        
 [4] haven_2.2.0         lattice_0.20-38     labelled_2.3.1     
 [7] colorspace_1.4-1    vctrs_0.3.0         generics_0.0.2     
[10] htmltools_0.4.0     viridisLite_0.3.0   yaml_2.2.1         
[13] rlang_0.4.6         e1071_1.7-3         huxtable_4.7.1.9000
[16] pillar_1.4.4        foreign_0.8-71      glue_1.4.1         
[19] withr_2.2.0         DBI_1.1.0           matrixStats_0.56.0 
[22] lifecycle_0.2.0     stringr_1.4.0       munsell_0.5.0      
[25] gtable_0.3.0        htmlwidgets_1.5.1   forcats_0.5.0      
[28] knitr_1.28          crosstalk_1.1.0.1   class_7.3-15       
[31] fansi_0.4.1         htmlTable_1.13.3    Rcpp_1.0.4.6       
[34] KernSmooth_2.23-15  backports_1.1.6     checkmate_2.0.0    
[37] scales_1.1.1        DT_0.13.4           classInt_0.4-3     
[40] jsonlite_1.6.1      farver_2.0.3        expss_0.10.2       
[43] hms_0.5.3           digest_0.6.25       packrat_0.5.0      
[46] stringi_1.4.6       dplyr_0.8.5         grid_3.6.1         
[49] cli_2.0.2           tools_3.6.1         bitops_1.0-6       
[52] magrittr_1.5        lazyeval_0.2.2      RCurl_1.98-1.2     
[55] tibble_3.0.1        pacman_0.5.1        crayon_1.3.4       
[58] tidyr_1.0.3         pkgconfig_2.0.3     ellipsis_0.3.1     
[61] Matrix_1.2-17       data.table_1.12.8   lubridate_1.7.8    
[64] assertthat_0.2.1    httr_1.4.1          rstudioapi_0.11    
[67] R6_2.4.1 

Inizia eseguendo la riproduzione fornita con sf, ggplot2 e plotly e confronta il tooltip con e senza style(hoveron='fills'). Traccia l’output di ggplotly() e la gestione di hoveron; il lavoro è completato quando il tooltip testuale viene visualizzato correttamente per la mappa sf applicando hoveron='fills'.