I have this problem on a number of machines. Selecting two of them for example: Both 64bit windows 10, one with the anniversary update,
KB4022715, and outlook 2013, one with creators update,
KB4022725, and outlook 2010.
I looked at the permissions of the C:\ProgramData\Microsoft\Search\Data folders, and found permissions on one that I could view, and on another PC I couldn't enter the folder. so I assigned SYSTEM as owner to both, and gave
SYSTEM, local admins, users, and EVERYONE Full control over the folder. Indexing seems to be working better, at the moment anyway....
Now, I know very well that giving "EVERYONE" Full control over any folder is bad practice, so maybe someone can figure out exactly which permissions the search system needs in order to work correctly.