FOR THOSE DIDN'T TRY MY WORKAROUND;
I tried this on multiple machines, including my VMs and a low-end device having Win10 1909.
So, before you type a reply, please try my workaround. I can give you all 95% guarantee that it will work–even after a couple of restarts!
I know, I'm not working in Microsoft as a casual user. But I can clearly say I'm the one trying everything I know and giving a certain resolution.
Sorry about all these heat and if I said something wrong, I'm really sorry.
Hope you all are having a great day!
Bedirhan.
A not so experienced tech YouTuber.
Here's my resolution;
1-) Open command prompt window. It's important for you use it in user level since this will restart explorer and metro apps won't work in administrative privilege.
2-) Type these commands IN THE EXACT ORDER;
taskkill -f -im sihost.exe
taskkill -f -im SearchUI.exe
3-) Now try opening an explorer window and searching something. It should work.
Quick note: Disabling Windows search also disables Cortana and Explorer search in Windows 10 1909 since they all use SearchUI.exe but with different parameters. So, if you want to disable Windows search, keep these in eye.
Also, I'm planning to upload a video to my channel when I'm done editing. I'm not doing promotion. The video will be about this problem and using same method. But I'm doing this only for you all to understand. :)
You can both check from the link in my profile or wait for my notification here.