The reason can be many things, not allowed should be enough, imho. Will add, integrity can't be verified by checksum..
Your OS is cleaned up either try the in-place upgrade way or restore RTM components with this method, then try the switch https://forums.mydigitallife.net/threads/windows-10-hotfix-repository.57050/page-448#post-1544947
That answer comes from the less knowledgeable users of this forum seeming to think that there are resident psychics amongst our ranks.
For users like @endbase and @SM03 , their search box seems to be buggy but that's not the case for @Enthousiast , all of them being on the same build 18363.418. There can be many reasons for this, including the respective tweaks that may or may not be done on the individual systems. First of all, its just my guess, but if its at all helpful, I would like to point out that the enablement packages are apparently different for builds .418 and .3xx. Since all other updates(CU,SSU) being the same and this(EP) being the only difference, I am just putting it out there.
I found out what is causing it on my computer it's a skinning program derinstalled that all good but I don't like how the new search works so went back to 1903 for now
maybe this week sometime as internal employees getting oct 16 onwards; and they make us on 10022 suffer til they give us in next few weeks as per their windows insider blog useless slow ring as far as i am concerned so skipping future insider rings till rtm