I've moved your post to our ePO area for better attention by a product expert.
From which repository branch are we trying to update patch4? Is it from Current or Evaluation?
If from current branch then make sure then in the update task, we have selected VSE 8.7 under patches and service packs.
If from Evaluation then make sure that you have MA 4.5 patch1 and its extension checked into the ePO server.
If we have done this then may I have agent log and VSE install log file from the client machine.