This bug has morphed since originally reported in February. Today it does include the properties panel (or maybe it always did?).
However every time I restart with logging, I cannot replicate the issue and grab a log file.
It is not specific to any one file, either layout or content page, and after closing and re-opening, it works fine, so it doesn't seem like a parsing issue, but you'd obviously know better than me.
To me it feels like a timing issue on load.