RStudio 1.2.1335 aborting R sessions after STOPping R programs

I am using R3.5.1 on my WIN10 notebook to run Keras (R interface to Keras) 2.2.0.9000 and associated packages, in particular tensorflow (R interface to tensorflow) 1.9 and reticulate (interface to Python) 1.9. in order to do deep learning network development.
About a week ago I updated my RStudio from 1.1.456 to 1.2.1335. Since then, any stopping a running R program using the red STOP-button provided by RStudio inevitably leads to a complete session abort with a complete loss of all data acquired/produced and functions installed so far. It is then invariably necessary to restart a new session from scratch - a quite tedious process.
This was not what used to happen with the previously installed RStudio version 1.1.456.
Any suggestion what I could do to prevent this happening?

Can you provide a reproducible example? It would also be useful to have your R and Python session info -- that is, the output of:

sessionInfo()
reticulate::py_config()

Hi, Kevin
These are the outcomes of the two commands after a regular termination of the programm, i.e. execution until the last line. Pls see below.
It will be difficult to produce a 'reproducible example' because not only has the program almost 2000 lines by now; as soon as I klick the red STOP-button, the program stops, RStudio remains inaccessible for a few seconds - and then, suddenly, the message "R session aborted" appears, see pic.

R%20Session%20aborted

I can only get rid of this message by pressing the "Start New Session"-button shown and at the same moment everything is lost. I'm unable to recover any diagnostic information provided in principle by RStudio help facilities.

sessionInfo()
R version 3.5.1 (2018-07-02)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 17763)

Matrix products: default

locale:
[1] LC_COLLATE=German_Germany.1252 LC_CTYPE=German_Germany.1252
[3] LC_MONETARY=German_Germany.1252 LC_NUMERIC=C
[5] LC_TIME=German_Germany.1252

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

other attached packages:
[1] ggplot2_3.0.0 keras_2.2.0.9000 tensorflow_1.9
[4] reticulate_1.10 RevoUtils_11.0.1 RevoUtilsMath_11.0.0

loaded via a namespace (and not attached):
[1] Rcpp_0.12.18 pillar_1.3.0 compiler_3.5.1
[4] plyr_1.8.4 bindr_0.1.1 base64enc_0.1-3
[7] tools_3.5.1 zeallot_0.1.0 jsonlite_1.5
[10] tibble_1.4.2 gtable_0.2.0 lattice_0.20-35
[13] pkgconfig_2.0.1 rlang_0.2.1 Matrix_1.2-14
[16] rstudioapi_0.7 bindrcpp_0.2.2 withr_2.1.2
[19] dplyr_0.7.6 grid_3.5.1 tidyselect_0.2.4
[22] glue_1.3.0 R6_2.2.2 purrr_0.2.5
[25] magrittr_1.5 whisker_0.3-2 scales_0.5.0
[28] tfruns_1.4.0.9000 assertthat_0.2.0 colorspace_1.3-2
[31] labeling_0.3 lazyeval_0.2.1 munsell_0.5.0
[34] crayon_1.3.4

reticulate::py_config()
python: C:...\AppData\Local\conda\conda\envs\r-tensorflow\python.exe
libpython: C:/.../AppData/Local/conda/conda/envs/r-tensorflow/python36.dll
pythonhome: C:...\AppData\Local\conda\conda\envs\R-TENS~1
version: 3.6.6 |Anaconda, Inc.| (default, Jun 28 2018, 11:27:44) [MSC v.1900 64 bit (AMD64)]
Architecture: 64bit
numpy: C:...\AppData\Local\conda\conda\envs\R-TENS~1\lib\site-packages\numpy
numpy_version: 1.14.3
keras: C:...\AppData\Local\conda\conda\envs\R-TENS~1\lib\site-packages\keras_init_.p

NOTE: Python version was forced by use_python function