I need an explanation regarding the behavior of my wallet.
I just mined a few coins and the balance become 2 times smaller (half of the coins disappeared).
"wallet check passed" : true
In blockchain explorer everything looks good, but situation its still confusing.
Now I waiting to mature the mined coins to see what will happen.

they didn't disappear, they just show up in the staked category, which is where you can see how how many coins you are earning interest on. Once the staked amount is processed, the coins will show up in your main balance along with the interest that was accumulated.