Error: Unsupported numpy type: NPY_INT

I was following the tutorial in https://blogs.rstudio.com/ai/posts/2019-05-06-tadpoles-on-tensorflow/ but I'm getting the error:

+ Error in py_call_impl(callable, dots$args, dots$keywords) :
ValueError: Failed to convert a NumPy array to a Tensor (Unsupported numpy type: NPY_INT).

right after calling:

+ res = hmc %>% mcmc_sample_chain(
+ num_results=n_steps,
+ num_burnin_steps=n_burnin,
+ current_state=initial_logits,
+ trace_fn=trace_fn
+ )

any idea what is causing it?

Here is my sessionInfo():

sessionInfo()
R version 3.6.2 (2019-12-12)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 19041)

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] parallel  stats     graphics  grDevices utils     datasets  methods  
[8] base     

other attached packages:
[1] zeallot_0.1.0          tfprobability_0.11.0.0 tensorflow_2.2.0      
[4] rethinking_2.01        dagitty_0.2-2          rstan_2.19.2          
[7] ggplot2_3.2.1          StanHeaders_2.19.0    

loaded via a namespace (and not attached):
 [1] reticulate_1.18    shape_1.4.4        tidyselect_0.2.5   purrr_0.3.3       
 [5] lattice_0.20-38    generics_0.0.2     V8_3.0.2           colorspace_1.4-1  
 [9] stats4_3.6.2       loo_2.2.0          base64enc_0.1-3    rlang_0.4.8       
[13] pkgbuild_1.0.6     pillar_1.4.3       glue_1.3.1         withr_2.3.0       
[17] rappdirs_0.3.1     matrixStats_0.55.0 lifecycle_0.1.0    munsell_0.5.0     
[21] gtable_0.3.0       mvtnorm_1.1-0      coda_0.19-3        inline_0.3.15     
[25] callr_3.4.0        ps_1.3.0           tfruns_1.4         curl_4.3          
[29] fansi_0.4.1        Rcpp_1.0.5         scales_1.1.0       jsonlite_1.6      
[33] gridExtra_2.3      processx_3.4.1     dplyr_0.8.3        grid_3.6.2        
[37] keras_2.3.0.0      cli_2.0.2          tools_3.6.2        magrittr_1.5      
[41] lazyeval_0.2.2     tibble_2.1.3       crayon_1.3.4       whisker_0.4       
[45] pkgconfig_2.0.3    MASS_7.3-51.4      Matrix_1.2-18      prettyunits_1.1.0 
[49] assertthat_0.2.1   R6_2.4.1           boot_1.3-23        compiler_3.6.2    
>

rstudio / tfprobability

Error: Unsupported numpy type: NPY_INT #136