Home Axis does not reach Limit Switches using Raspberry Pi but works with laptop

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I have tried a few configurations and will attempt to walk you through these. In both configs I have a Uno with Grbl board. This board is being used to break out pins for Limit Switches and Stepper signals for external stepper drivers. The Uno is powered from the connected PC's USB cord.

When We have our Raspberry Pi with 7" screen connected to the Grbl board and attempt to home the system using single axis at a time mode [X then, Y then, Z] we observe often the Y-axis will make the initial contact with the limit switch but the second seek step will stop short > Move to the finale position and continue to home the final axis. When finished the system alarms with:
"An unexpected error was detected (ALARM:1} Hard limit has been triggered. Machine position is likely lost due to sudden halt. Re-homing...."

Now when I use my Laptop running OpenBuildsControl to power and control the Grbl board homing and control of the Steppers all work as expected.

I working on getting a external power supply for the Uno to power the Grbl board via the power jack of the Uno. Does this sound reasable that the Raspberry Pi maybe under volting the Grbl hardware? Or are there configs in UGS like denounce time