While editing a non-saved R Markdown document in RStudion with the "Chunk Output Inline" option selected the IDE was correctly generating outputs inline and everything looked. However, after I saved the file and gave it a name, the IDE stopped generating outputs inline. When looking for a possible bug online, I found a few mentions of this problem (can't post 2+ links because of new account) but no solution. I did found a topic mentioning that:
There's a BUG in the software where the files that are saved with "ó ã õ" characters are not displaying tibble objects and plotly objects
In order to test this, I created a very simple .Rmd file, copied it and gave each copy a different name, one with ASCII characters only ("test") and the other with a non-ASCII character ("testá"). I found that although plots seem to be shown inline without problems in both files, data.frames (tibbles, and so on) do not show in the "testá" (the one with non-ASCII characters in its name).
My hypothesis is that RStudio stops showing output inline when file has non-ASCII character in its name. Note that I only tested this with the "á" character. This is not expected, since the file name should not interfere in how inline output is shown.
Here is the content of both files in case you want to test without downloading my files.
plot(cars) test <- data.frame(x = c(1,2), y = c("?", "a")) test
I am using RStudio 2022.12.0+353 "Elsbeth Geranium" Release
(7d165dcfc1b6d300eb247738db2c7076234f6ef0, 2022-12-03) for Windows
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) RStudio/2022.12.0+353 Chrome/102.0.5005.167 Electron/19.1.3 Safari/537.36
R version 4.0.5 (2021-03-31) Platform: x86_64-w64-mingw32/x64 (64-bit) Running under: Windows 10 x64 (build 19044) Matrix products: default locale:  LC_COLLATE=Portuguese_Brazil.1252 LC_CTYPE=Portuguese_Brazil.1252  LC_MONETARY=Portuguese_Brazil.1252 LC_NUMERIC=C  LC_TIME=Portuguese_Brazil.1252 attached base packages:  stats graphics grDevices utils datasets methods base other attached packages:  forcats_0.5.1 stringr_1.4.0 purrr_0.3.4 readr_2.1.2  tidyr_1.2.0 tibble_3.1.6 ggplot2_3.3.5 tidyverse_1.3.1  dplyr_1.0.8 loaded via a namespace (and not attached):  bslib_0.3.1 tidyselect_1.1.2 xfun_0.30 haven_2.5.0  colorspace_2.0-3 vctrs_0.4.1 generics_0.1.2 htmltools_0.5.2  yaml_2.3.5 utf8_1.2.2 rlang_1.0.2 jquerylib_0.1.4  pillar_1.7.0 glue_1.6.2 withr_2.5.0 DBI_1.1.2  dbplyr_2.1.1 modelr_0.1.8 readxl_1.4.0 lifecycle_1.0.1  munsell_0.5.0 gtable_0.3.0 cellranger_1.1.0 rvest_1.0.2  evaluate_0.15 knitr_1.38 tzdb_0.3.0 fastmap_1.1.0  fansi_1.0.3 highr_0.9 broom_0.8.0 scales_1.2.0  backports_1.4.1 jsonlite_1.8.0 fs_1.5.2 hms_1.1.1  digest_0.6.29 stringi_1.7.6 grid_4.0.5 cli_3.2.0  tools_4.0.5 sass_0.4.1 magrittr_2.0.3 crayon_1.5.1  pkgconfig_2.0.3 ellipsis_0.3.2 xml2_1.3.3 reprex_2.0.1  lubridate_1.8.0 assertthat_0.2.1 rmarkdown_2.14 httr_1.4.2  rstudioapi_0.13 R6_2.5.1 compiler_4.0.5