its not that "i believe" its a bug, its that "it is one"... I have logged a ticket and I'll post progress. I dont think I'm the only individual with this issue. So likely theres others. As per screenshots only one slot is visible, theres notice for completed researched (red dot on the left hand side...

Also here's my actual building research ^^

I have exact same issue. Problem was i accidentally spent currency to speed up existing research to be able to access "hidden in the background" complete research. And now ive the same thing again. I took the screenshot. Ive 2 slots researched but only one visible and im not also 120+ something curr...