Internal pdf viewer displays mostly blank pages

I recently upgraded to rstudio rstudio-2022.12.0-353-amd64.deb on both a desktop and laptop, both running Linux Mint MATE 21.1. When I clicked knit for an Rmd vignette, the internal pdf renderer displayed mostly blank pages on the desktop. Went and tried the laptop, and no problem. Downgraded on desktop and all fine. (System viewer also works in both "old" and "new" versions.) Upgraded again -- same issue. Also noted that the pdf is not saved for some reason.

Not critical, but annoying.

JN