I had been using Windows 8 and TortoiseSVN icons have been displaying properly, but after installing Windows 10 I can no longer see the icons for the files/folder status.
As others have indicated, the overlay icon registry area is congested. Here is a powershell script that allows you to dump all the overlays in the registry to a file, then after you edit the file to prioritize your overlays the way you want, you can import them back in and protect them against further modifications from other programs running under SYSTEM.
https://github.com/polachz/OverlayIconFix