(And that makes sense, we tend to focus on our own country and environment.)
The first thing I hear from any ex-Soviet who grew up in the USSR is how their lives were impacted by the constant shortages and censorship of issues with the supply chain. There's a classic joke from the USSR that goes:
"Comrade, aren't you excited for when the USA finally falls?"
"No, who will we buy our grain from?"
Another one:
"Isn't it true that the USA is rotting from within?"
"Yes, but what a smell!"
Millions of people in the USSR starved to death, and their consumer tech was among the most unreliable and poorly-made available internationally. This despite Soviet mathematicians and engineers being among the finest and hardest-working on the planet. They could only just overcome the constraints that the centrally-governed economy placed on them. The only notable exception is military hardware, which was actually funded.
What do you mean "it's obviously not true [that the Soviet economy didn't work]"?
A guy walks into the store, looks mournfully at the bare shelves, and asks the worker at the counter, "So, comrade, you don't have any meat today, do you?"
"Comrade, did you not read the sign at the entrance? This is a seafood market; we don't have any fish. The meat shop is across the road - they don't have any meat."
To me, while we might see many many problems within the Soviet economy and see many ways it could have been better, it is clearly not an economy that "didn't work". And by some measures, we can even say it "worked" better than the post Soviet economy.
After the '91 collapse Western scholars briefly got their hands on some Soviet archives and worked to piece this together. The Soviet economy was run by fixers; Party people that answered to Party leadership and mediated the difference between the State's official socialist schemes and reality. The system was opaque and kleptocratic in the extreme and, except for a brief period after the collapse, it appears not much has changed.
A concise survey of the archives can found found in: "Behind the Facade of Stalin's Command Economy: Evidence from the Soviet State and Party Archives" (Paul Gregory, 2001).