I did all of the above and nothing worked. The overlay icons were appearing in Explorer but not in Total Commander.
Eventually what solved the issue for me was that I discovered a command in Total Commander that refreshed the Overlay Icons. To access it, right click on the toolbar and click on "Change...", and add "cm_SwitchOverlayIcons" as shown in the image below.
After adding the command icon to the toolbar, I click it once, and the overlay icon of TortoiseSVN appeared!