File Associations aren't reassigning

RS4 WR2.0.3
I am using all of the Optimisation features, I'm a little suspicious of the Registry cleanup (how can there be a 600% improvement? Surely there can't be that much junk...)

Anyway the symptom is that I can't reassign .txt to use notepad++ using the "Open with"/"Choose another app"/"Always use this app to open (file ext) files": its always stuck with the original notepad.
If I open Task Manager I can see that the file association program "Pick an app" which is C:\Windows\System32\OpenWith.exe seems to be stuck running. I can't reassign other file types with different applications either.

Has anyone run into this before?

Edit: I read this other Open With post but that seems to be a problem with the Open with context menu not even displaying? My problem is not that it opens, but is that the "Always use..." part doesn't reassign a file type to a program

Hello

1) About the "Registry Optimizer" option, this is confirm by my own test ... with my "Desktop" wccf, the registry size footprint can be reduced by 600% ... and it will reduce even more if you use more components, like in v3.0.4.0 with my "Desktop" wccf .... the registry size can be reduced from 36.5MB to 3.44Mb !!!!  
Of course, this is not the biggest component available but still, the 600% is a realistic value

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2) Yes as described in this post (below), I can reproduce the open with bug with a non modified operating system, so this should be a Windows bugs and not one from WinReducer :
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I'm able to solve this issue by keeping both :
- "Accessories - Notepad"
- "Accessories - Paint"
==> To solve this Windows "open with" issue, you need at least 2 available software in the open with list ... otherwise it will not work properly. But in RS5, the bug is partially solve because the "Always use this app" option works correctly with all files except "*.txt" files  

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3) Just for the record, I will release tomorrow my "Desktop" wccf (with many information), in which the "open with" menu works correctly (for this I to keep keep notepad and paint) and I activate the registry optimizer among many other things

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Have a great day !