I don't know if it is related, but it looks like a lot is missing in the download e.g. the support-v4 jar files and the google-play services. In fact, the whole folders c:\android\extras\android seems to be missing (which has the folder support) and the folder c:\Android\extras\google\google_play_services does not exist either.
I didn't unselect/select any other than the recommanded ones.
Attached is the (rather long) log from the SDK Manager.
EDIT: and the installed-components.txt file from the C:\Android\extras\b4a_remote folder.