Here’s an update on the issue where “Send To LayOut” is greyed out, and sometimes the dock icons can turn into question marks.
We’ve talked to Apple - this issue is a side effect of some security improvements that they made in Sierra. For most users, you’ll just have to wait until we can get another bug fix out the door. If you’re an advanced user, start reading up on “app translocation” and the quarantine xattr “com.apple.quarantine”. In theory, deleting the quarantine flag will stop the translocation system from running SketchUp from a temporary location.