In addition I tried to install in local the last version of PS 1.7.5.1 and the bug has not yet been solved.
I took a product that already existed in the test catalog, I made the color WHITE available in size S and M and the BLACK size L
obviously the BLACK L variant cannot be selected in any way. (I set "Show product attributes not available on the product page" to NO)
But is it possible that such a huge bug like this has not been detected by anyone?