I can't reproduce the problem, of course, without the code, but I've been running sf without difficulty. Here's what I have after loading the same packages:
sessionInfo()
R version 3.5.3 (2019-03-11)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 18.04.2 LTS
Matrix products: default
BLAS: /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.7.1
LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.7.1
locale:
[1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C
[3] LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8
[5] LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8
[7] LC_PAPER=en_US.UTF-8 LC_NAME=C
[9] LC_ADDRESS=C LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] rgdal_1.4-3 sp_1.3-1 leaflet_2.0.2 sf_0.7-3 dplyr_0.8.0.1
loaded via a namespace (and not attached):
[1] Rcpp_1.0.1 rstudioapi_0.10 magrittr_1.5 units_0.6-2
[5] tidyselect_0.2.5 lattice_0.20-38 xtable_1.8-3 R6_2.4.0
[9] rlang_0.3.4 tools_3.5.3 grid_3.5.3 packrat_0.5.0
[13] e1071_1.7-1 DBI_1.0.0 htmltools_0.3.6 crosstalk_1.0.0
[17] class_7.3-15 assertthat_0.2.1 digest_0.6.18 tibble_2.1.1
[21] crayon_1.3.4 shiny_1.3.0 later_0.8.0 purrr_0.3.2
[25] htmlwidgets_1.3 promises_1.0.1 mime_0.6 glue_1.3.1
[29] compiler_3.5.3 pillar_1.3.1 classInt_0.3-1 httpuv_1.5.1
[33] pkgconfig_2.0.2
>
What would worry me most is Ubuntu, R, dplyr, Rcpp, rstudioapi, compiler ... just say everything that's not current. I'm not a cloud user, so I don't know whether you, as a user, can do all of that.