Hello,
There is little trick when creating the bot. Locate the code that connects a bot on the server(CREATE_FAKE_CLIENT in bot.cpp) and there you will see setting some client values like "cl_updaterate". There you need to add one more:
Code:
SET_CLIENT_KEY_VALUE(clientIndex, infobuffer, "_vgui_menus", "0");
This should get the bots joining a team.
P.S. Also note that there is other issues that are present in HPB_bot that are not fixed because of missing maintainer, like this snipped from E[POD]bot that will fix your server behave strange and crash when you kick a bot.
Code:
// Fix from Pierre-Marie Baty
if (BotEnt->pvPrivateData != NULL)
FREE_PRIVATE(BotEnt); // free our predecessor's private data
BotEnt->pvPrivateData = NULL; // fools the private data pointer
BotEnt->v.frags = 0; // reset his frag count