None too sure as I have downloaded the full installers from the relevant page(s).
But I wonder if the GUI update not receiving the most current or as seems to be described above…re-downloading the same one? Is due the change(s) made to the “installer” being changed not too long ago i.e. if the version in GUI updater is the old installer it will not detect the newest version with the new installer.
Does there need to be some clarity injected by the Topaz team…probably.
PS of note this was said on the page about GAI version 4.5 here Gigapixel AI v4.5.0 and my surmise is that Sharpen & DeNoise has seen similar installer changes 
Improvements
** New installer framework (can keep old one installed)**
