Okay weird - so I initially started it up manually using the command line (as above). I then restarted (still no panel), so launched it manually again and just did my things. Then the next time I restarted, it did show up. Haven’t had issues ever since.
(So I didn’t get to try those suggestions stargazer, but thanks for the comments hopefully may be useful of others if they have issues).
My best guess is that some file got wiped out/replace during the update, and perhaps caused the launcher to fail to start. Perhaps launching it manually/using it for a while allowed xfce to recreate whatever file/config was missing, so it now launched succesfully?