Custom fields disappear

[reachgvm]

I added few fields to CRM Lead using customize form. After a while, the fields disappear where I don't see that fields in the leads page. When I try to add through leads page view, I can't those fields at all. But when I went into the database table, I can see still the custom fields there.

Then I had to add manually those fields back again using customize form.

This happened already few times.