I have the same problem. I contacted Dell Tech support over a week ago and they have done nothing or suggested very little.

I have tried everything with the Dell optimizer application update to get it installed. Dell is hopeless, after 2 weeks they have suggested on numerous occasions to upload log files, but then do nothing.
So what I have done to date.

*Reinstalled windows with a fresh copy. Tried to install Dell Optimizer again.(had to reinstall all my settings and apps because of this, after trying to upgrade the optimizer app) No difference, still doesn't install.
*Scanned hardware, all good (plus very new Dell XPS)

*Turned off all services except windows services, tried to install optimizer again. Doesn't install.

*Reinstalled all software from the Dell website, all installed except the Optimizer application. When trying to install it comes up with a error asking for the location of the optimizer.msi on a CD or DVD, which obviously I don't have.

I'm at my wits end trying to figure it out and as I have said Dell customer service is hopeless, lacking basic software knowledge.

The fact that if I run Dell SupportAssist, "Boost Performance" it optimizes the drive, plus if I go to the Dell website and run check for updates it comes back as saying there isn't any updates.

This is a screenshot of updating Dell Optimizer from the Dell SupportAssist, notice it say "Installed" yet run the app again after rebooting and it say to upgrade the same app.