What could be the reason UE sends RRC Reestablishment Request after SgNB Addition? (EN-DC)

Hi everyone,
After UE successfully attaches 4G, 5G attach begins. But after eNB sends EEC Reconfiguration message to UE, it receives RRC Reestablishment Request from UE. What could be the reason behind this problem?

I am having this with a Xiaomi Mi11:

  1. eNB send RRC rcong to add NR freq
  2. UE adds NR freq
  3. eNB send RRC recong to add LTE-CA-Scell
  4. UE replys with Reconf_failed
  5. UE performs RRC_Restablish on annother LTE CELL

what was the root cause ?
What did you do to fix it ?