To ensure that the rectangle object is unlocked and selectable for editing in the PCB layout, please open the rectangle's properties panel and check the lock status. If the object is locked, toggle off the lock option so that you can freely select and modify its dimensions.

To center the selected Circle Shape on the PCB, please ensure that the object is unlocked and then manually update its position properties. In the PCB layout editor, verify the board's center coordinates (often the origin, e.g. (0,0), if your board is referenced from its center) and then set the Circle Shape's position to those coordinates. If available, enable the snap-to-grid or center alignment feature to assist with precise placement.

You can create a hole in your PCB by defining a drill hole as part of a pad or by using a dedicated mechanical shape tool designed for fabrication openings. For detailed instructions on how to set up and configure these holes (including specifying drill sizes, positions, and layer assignments), please refer to the Flux documentation on PCB holes here:

Additionally, you may post in the Flux User Community if you need specific guidance or troubleshooting tips.