Question: Why is Maple missing solutions?

Hi, I ran the following code:

solve({a > 0, b*d*(abs(c)^2-abs(a)^2) = 0, -a*c*(abs(b)^2-abs(d)^2) = 0, -abs(b)^2*a*d+abs(d)^2*b*c = 0, abs(c)^2*a*d-abs(a)^2*b*c = 0}, {a, b, c, d})

and we can easily see that a=a, b=0, c=0, d=d, should be a solution but Maple does not give me that answer. The result is:

{b = 0, c = 0, d = 0, 0 < a}, {b = 0, c = a, d = 0, 0 < a}, {b = d, c = a, 0 < a, 0 < d}, {b = 0, c = -a, d = 0, 0 < a}, {b = -d, c = -a, 0 < a, d < 0}, {b = d, c = a, 0 < a, d < 0}, {b = -d, c = -a, 0 < a, 0 < d}

Am I missing something?

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