Our vehicles are known for this issue. I'm willing to bet your filters are fine. What happens is when your XK sits all the fluid drains out of the torque converter. When you start your XK in the morning, let it warm up for a few minutes. Then when you shift out of park to either reverse or drive, give it an extra second before you step on the gas.

When i replaced both filters and fluid on my trans it still continued to do it. But I now let it warm up and wait an extra second before romping on the gas