Bf4 Commander mode

Probably it's just a glitch - I have checked and it seems that I can connect as Commander on HC server without any issues (via PC). Were you trying to get on Rush servers by any chance? These have Commander disabled by default now.

Then it probably is some sort of a new bug, as I can find these servers and join them properly via Battlelog on my laptop. Still, could you please post all the search settings that you chose (region, number of players etc.)? I honestly doubt that it's search-related, but it wouldn't hurt to try.

I can get into HC servers on my Andriod tablet without any problems.  You just need to make sure that there is nobody in the que for that server, otherwise you can't get in (I know, stupid bug on the commander app end, works find if on the PC).

Rick is correct, right now joining the servers with queue as a Commander doesn't seem to work (even if they have empty commander slots).

Maybe enough people joined between you finding the server on Balltelog and you hitting the commander button?  I've had that happen before.