It was possible in GC2 as well.

It sounds like a bug. 

Personally the 1 tech per turn is fine. Its how the game was designed. I would check your turn counter and see if you are flipping turns with each tech.

This does not at all seem like a bug, it seems like a design feature to address the situation specifically brought up by the OP, when you are in the late game and have a bunch of low level techs still not researched....the idea of one tech per turn seems like a very arbitrary and unnecessary limit that penalizes you for playing well and having good research....considering this is exactly how it worked in GC2, I don't see how you can say that 1 tech per turn is "how the game was designed"...

I would be very displeased if a 1 tech per turn limit were implemented into this game, some people like to play on faster settings and many people only research one weapon type for most of the game...

Some of the Benevolent ideologies and anomaly bonuses also give lump sums of research...

At the same time however, it's seemingly intentional that we are unable to build higher level improvements, ex. an Xeno Factory, in a single turn if we have the manufacturing to do so. Is there a dev stream planned for today, Larsenex?

Yeah it was listed in one of the recent patch notes ( cant remember if it was like .8x or 1.0) but they stated that research was fixed so that if you had excess it counted properly i asked if we could theN research 2 or more techs per turn and the answer was yes but they hadnt seen it

Ok cool, they wouldn't have seen it unless they selected the future tech on the tech tree instead of just picking the one of the available techs on the cut down version, since the game doesn't know where to apply the excess research otherwise.  Not a bug, but it gives people the choice to either play one tech per turn (use the cut down research selector) or use the tech tree to expend all research at once.