I've started researching the new Nuklear something in the Light Tank tree... and next day the "current" research disappeared.. I can't see what's being researched and when I try something else it says both slots are taken. Oh and I only see Infantry, can't click on Armor, Air or any other tab.
Game 1448548
This is a known bug, the devs are working on it.
In the mean time do not research any of the bugged items, as they don't give you any new unit and your resources and time spent on them will be lost.
Best Regards,
WildL
EN Community Support
Bytro Labs | Call of War
I don't know if you should have researched that. 
Hey guys,
This issue should now be resolved hopefuly. I am now closing this thread
