You have to enable bot thinking AND activate tutorial mode, if you do both does things, they will work. If you only enable bot thinking, then the bots will only work in tools mode or on steam with cheats mode on.
Below is the “addon_game_mode.lua” from Next Generation mod, which fills empty slots with bots in strategy mode and then activates tutorial mode in the early game stage.
If you are interested, we are working on a framework for modmakers that facilitates making more interesting bots for dotalikes, e.g. replacing their item builds, skill builds, abilities and wearables.