What is the reason for drop because of partial handover?

What is the reason for drop because of partial handover?

ERAB_REL_HO_PART_QCI1

Anyone having idea for VoLTE Drop?

It can be due to cs+ps handover definition.
Qci1 with ps handover.
Partially cs handover but ps drop.
Change it to cs only …this definition per neighbours.

Ok thanks!
Any connection with MME side?

Yes same parameter in MME also.