Materialized view with aggregate function incorrectly shows it allows incremental rebuild

set hive.support.concurrency=true;
set hive.txn.manager=org.apache.hadoop.hive.ql.lockmgr.DbTxnManager;

create table store_sales (
  ss_sold_date_sk int,
  ss_ext_sales_price int,
  ss_customer_sk int
) stored as orc TBLPROPERTIES ('transactional'='true');

insert into store_sales (ss_sold_date_sk, ss_ext_sales_price, ss_customer_sk) values (2, 2, 2);

create materialized view mat1 stored as orc tblproperties ('format-version'='2') as
select ss_customer_sk
      ,min(ss_ext_sales_price)
      ,count(*)
 from store_sales
 group by ss_customer_sk;

delete from store_sales where ss_sold_date_sk = 1;

show materialized views;

explain cbo
alter materialized view mat1 rebuild;

# MV Name           	Rewriting Enabled   	Mode                	Incremental rebuild 
mat1                	Yes                 	Manual refresh      	Available           

CBO PLAN:
HiveAggregate(group=[{2}], agg#0=[min($1)], agg#1=[count()])
  HiveTableScan(table=[[default, store_sales]], table:alias=[store_sales])