China may nominally be a Communist country, but in practice, they've been more an authoritarian capitalist state for a generation or two now.

Are there examples where communism did not turn into authoritarian?

Is that pertinent to whether or not China is currently communist in anything but name only? No.

I'm genuinely curious because all we hear about are the bad examples

I’ve been wondering the same but maybe we only have these examples because the only successful attempts to forcefully take power away from the capitalists has been by authoritarians.

or maaaybe communism is just not working.

Cuba isn't doing too badly even though it's authoritarian. It's no soviet union, DDR or North Korea. The biggest problems they have are due to US sanctions.

But I think extremes never work. Neither strict communism nor all-out capitalism.

The state owns most if not all industry. The only thing that individuals can invest in is property. How is that capitalism?

State capitalism: https://en.m.wikipedia.org/wiki/State_capitalism

Can you differentiate state capitalism from Communism? Sounds like a No True Scotsman argument.

https://en.wikipedia.org/wiki/No_true_Scotsman

It's pretty simple - communism is "real communism" when it works, and it's not when it doesn't. It's similar to how it's not "real capitalism" when things go wrong in a capitalist system.