I think it has to do with how many research points are required to complete a technology. What works for me is to select a technology one or more steps beyond the one you want to research. Then hit "4" a few times. It will still show multiple turns required. End the turn and move on to the next turn. Once you've reached the next turn, open the technology display and you should see that all the techs. require only one turn except the one you want. Now hit "4" again and click on your desired tech. It will then show one turn required. The next few techs. should also require only one turn. Repeat the process as needed as you move farther up the tech tree. This should solve your problem!
Hit "7" and it will reset to max polocy points. Then Hit "7" again and it will reset policy points to zero. You can then proceed to the next turn.