I just installed the beta and was trying to read some dev plan documentation that I built that included a mermaid chart. It didn't render. I presumed, based on previous versions that there was just a rendering config to turn on. I was correct.
As a side note seeing triple-backtick mermaid in the content would be cool place for a chip that takes you to the config to turn on mermaid.
Anyway, I turned it on, pressed refresh at the settings, still no mermaid.
Quitting and restarting the app did render the mermaid chart.
Using the product more, I wonder if the actual issue was that it takes a little time to render the mermaid chart. If that's the case, maybe this is a feature request to have some sort of a "mermaid chart loading" indicator.