No posts added in the third block

Hi, I added three blocks (but I’d add 5 of them) and the first two are ok (with 2 or 3 posts for each category). The problem comes with the third one.
I use a particular category (VR) and no posts show up.
I upload a screenshot of what happens: https://postimg.cc/ThJqkPHk

Not only, I tried using one of the two categories that are ok and with them, the third one works fine. So, now I have 3 categories: 2 are ok (and they show up even in the third block) but 1 are not ok.
I also tried to create a new category, but nothing. It woks only with those 2 categories.
Furthermore, what sound strange is that I tried the same steps in another website and it works fine.
So, I really don’t know what else to do.

All the category are done in the same way. There are no differences among them.

Thank you for any suggestion.

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