SupportAssist Version 3.13.0.236

I was seeing similar results. 'Clean files' appeared to be stuck at 55% for a good 10 minutes. It eventually went to 85% and pretty smoothly after that. 

It seemed to have the most trouble while scanning for "unwanted system log files." Maybe you could remove these manually? I'm not sure where they all are, but some googling will probably turn up some lists.

(My SupportAssist is 3.13.0. I'm not sure about the .236.  Latitude 7420, Windows 11 22H2.)

After a couple of weeks of the same SupportAssist failure to work result, I resorted to removing the SA using IObit Uninstaller and selecting the option to delete residual files.  I then downloaded a new, clean copy of SupportAssist installer from the Dell website and SupportAssist installed fine and has run without issue since.  BTW, for full SupportAssist Version No. go to Settings icon and select About.

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The next (repeated and previously posted but no solution offered) problem that surfaced is that it's no longer possible to pin MS Office or Abobe files to their respective taskbar shortcuts despite this option still showing.  Internet posts suggest corrupt Windows account - but I've since installed PDF X and pinning files works making a corrupt account being the issue questionable - and the solution is to create a new user.  MS remote support took me down that rabbit hole the last time I had this problem; 2 hours remote time didn't fix the issue and left me with a mountain to climb reinstalling apps and 3rd party s/w. 

The other web suggestion is that the registry has been corrupted but the offered solution fails to install 'missing' entries.

Eventually fixed through full MS Office delete then Dell reset (twice).