Trying to see if this is expected behavior or not, as some of my end-users indicated they did not have the problem until last year. I only started this position a few months back, so am going off of their word.
When using the knit button, our RStudio-Server (Community) instance calls the following command:
<path-to-R>/R --no-save --no-restore -s -e rmarkdown::render('<R Markdown file>')
This works okay, unless someone gets disconnected and has to re-login. When logging back in, the command appears to get killed, and so end-users have to restart the knit process. I've confirmed that if the end user does not log back in, the knit process does continue in the background, meaning they could theoretically let it keep going until it finishes, but just not log back in. This behavior is also present if opening up a new tab of RStudio.
I've tested and confirmed that this happens on new installs, regardless of the RStudio-server version.