I don't know your age.
I assume you learn more from western economy.
If we abandon political bias,
the answer will be much straight-ward.
Normally speaking, inventory is not a part of fix asset investment.
It is called raw material , work-in-process and finished product.
Yes, you are right, it is part of investment, in your term, "general capital".
I happened learn those from both sides: Marxism and modern economy.
I believe the latter is much more convincing.
I hope this helps.