ORA-02149 error during adding a list sub partition to partitioned table

Database version: 18C

Issue with adding subpartition to exiting interval-list composite partitioned table. The error message:

ALTER TABLE TAB_PART

   MODIFY PARTITION coi1_2019

    ADD SUBPARTITION coi1_2019_EVENT_CD_PDFP

    VALUES ('PDFP')

Error report -

SQL Error: ORA-02149: Specified partition does not exist

1. 02149. 00000 -  "Specified partition does not exist"

*Cause:    Partition not found for the object.

*Action:   Retry with correct partition name.

But the partition coi1_2019 exists. Here are queries

select table_name, partition_name from user_tab_partitions;

TAB_PART     coi1_2018

TAB_PART     coi1_2019

TAB_PART     coi1_2020

TAB_PART     coi1_2021

select table_name, partition_name, subpartition_name from user_tab_subpartitions;