Using Free5GC Stage 1, UE only shows LTE, gNB didn't switched to 5GNR mode

We noticed that when testing the gNB connecting to free5GC stage 1, UE(5G NSA) only shows LTE, never changed to 5G mode. Is this expected? When we connecting to another EPC, the UE was able to show 5G mode. Is this because we are using the wrong stage of free5GC?