In the following figure, a create_clock constraint was defined on
the MMCM instance pin CLKOUT0. This overrides the
automatically derived clock created by Vivado and
loses any relationship with the incoming clock.
To just rename the auto-derived clock, use the following constraint right after the master clock definition in your constraint files:
create_generated_clock -name clkName [get_pins clk_gen_i0/clk_core_i0/inst/mmcme3_adv_inst/CLKOUT0]Figure 1. Invalid Primary Clock on Clock Modifying Block