I had, actually still have, this problem.
Since you are losing all 3 cameras, it is likely the connection to the radio wire. Look underneath the dash for a common audio/visual patch cord connection. I had to jiggle/twist this connection on more than one occasion, especially after driving bumpy roads. I may try and tape the 2 together. Fortunately, mine does not seem to be the connection to the back of the radio which I do not have as much access too, the wires I need to deal with are hanging down lower.
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