Q: All mounts were replaced but loud click sound coming from driver front wheel or tranny. Shop unable to identify if bearing or hub?

I replaced all motor and transmission mounts and did a drain & fill of the OEM ATM fluid and 2 months later I hear a loud click from the driver front wheel or the transmission itself when I shift from Park to Reverse and to Drive. It makes the sound when you move from a complete stop. While driving at any speed there is no noise. Took it to two different shops and they were unable to identify if it was the wheel bearing or wheel hub even after using a stethescope. Both components are still in working condition and they determined it was something inside the transmission itself. It shifts fine like normal while driving it's just a sound when at a stop. Fluid is still red. As a last resort I may do a total flush of the fluid but not sure if it will help.

My car has 242445 miles.
My car has an automatic transmission.