Another possible cause & fix to this issue
For me, the non-responsive start button & Cortana issue was caused by a corrupt log in the "TileDataLayer" database. My Application Event Log had these 3 errors times every time I clicked start:
EventID: 454 Source: ESENT
svchost (3148) TILEREPOSITORYS-1-5-21-1730992688-2170346420-2639683965-1001: Database recovery/restore failed with unexpected error -501.
Event ID: 465 Source: ESENT
svchost (3148) TILEREPOSITORYS-1-5-21-1730992688-2170346420-2639683965-1001: Corruption was detected during soft recovery in logfile C:\Users\USERNAME\AppData\Local\TileDataLayer\Database\EDB.log. The failing checksum record is located at position END. Data not matching the log-file fill pattern first appeared in sector 75 (0x0000004B). This logfile has been damaged and is unusable.
Event ID: 477 Source: ESENT
svchost (3148) TILEREPOSITORYS-1-5-21-1730992688-2170346420-2639683965-1001: The log range read from the file "C:\Users\USERNAME\AppData\Local\TileDataLayer\Database\EDB.log" at offset 307200 (0x000000000004b000) for 4096 (0x00001000) bytes failed verification due to a range checksum mismatch. The expected checksum was 4911804130253792991 (0x442a3bd52612e6df) and the actual checksum was 4911804130253792991 (0x442a3bd52612e6df). The read operation will fail with error -501 (0xfffffe0b). If this condition persists then please restore the logfile from a previous backup.
I was unable to find a way to rebuild or fix this database, if anyone knows a better way please do let me know as I'd like to get back my old configuration. I was however able to create & copy a new database to fix the issue. Instructions below assume that you don't have the technical knowledge or ability to put the drive into a 2nd system and preform the copy that way. They also assume that you are seeing the same problems I was in the Application Event Log.
1. Login to your current profile
2. Press WIN+X, and select "Command Prompt (Admin)"
3. Enter the following commands, in this order
1. net user "TempAdmin1" "password1" /add
2. net user "TempAdmin2" "password2" /add
3. net localgroup administrators "TempAdmin2" /add
4. Press CTRL+ALT+DEL, click Sign Out
5. Login to the "TempAdmin1" account using password "password1"
6. Logout, and then login to the "TempAdmin2" account, using "password2" (note: you must fully sign out, not just switch users)
7. Open File Explorer, select View, then check the box marked "Hidden Items"
8. Navigate to C:\Users\TempAdmin1\Local\TileDataLayer (click "continue" to gain access when prompted)
9. Right Click the folder "Database" & Copy
10. Now, navigate to the same folder for your damaged profile (C:\Users\YOUR_USERNAME\Local\TileDataLayer)
11. Right click "Database", and rename to "Database.BAD"
12. Right click empty area in the folder, and select Paste
13. Reboot, then sign back in with your original profile.
Now, assuming all is well, you want to delete the 2 accounts you created:
1. Win+X -> Control Panel -> User Accounts -> Manage Another Account
2. Select Account, then "Delete Account"
Hope that helps someone!