The datasheet for the ADF4108 eval board shows a schematic, but the schamic is using the ADF4107. It shows placeholders for values for the loop filter. The Bill of material shows values - but is it correct for the DF4108 or for the ADF4108.
Could you advise if the values and schematic shown are correct for the ADF4108 and what frequency the loop filter is tuned to?
In using the board, the performance doesn't appear as what would be expected by calculation with ADIsimPLL.