Thanks for reporting this (rather confusing) problem! I’ve had a look, and was able to reproduce it – no matter if preview pane or browser preview, I’m unable to load the RStudio preview in Gitpod. The preview stays blank or eventually shows an error.
However, from the console, I’m able to run
wget -O - http://localhost:8787 and see that the RStudio server is indeed serving HTML content.
Also, my browser’s console logs various Cross-Origin problems. Most notably:
Blocked loading mixed active content “http://8787-coffee-monkey-9v8x8je4.ws-eu04.gitpod.io/auth-sign-in?appUri=%2F%3FvscodeBrowserReqId%3D1619799125676”
… every time I refresh the preview. I wonder if this might be a bug in the IDE, or in Gitpod?
@akosyakov could you please take a look when you have time?