I've started to remove my extra runtimes.  Just an FYI - P8 crashed when I confirmed to remove a runtime that started with a number (the createively named 2009 Runtime).  However, when I restarted P8, 2009 was appropriately gone.

Also, for me, the ? marks have appeared in one category of the library, especially props, at the same time that other categories of library seem normal.  Also, some folders within a category will seem normal while others have ? marks.

Now that I've removed all of the external runtimes, the P8 content folder does not have ? marks (some categories did before).  I did not uninstall/reinstall.

I will add external runtimes back one-by-one later today.