Case and Bit_or in same query caused error

When running a query with

1. Group by based on a subquery + bit_or
2. Case when or IF()

It causes the error: Error Code: 1815. Internal error: IDB-2035: An internal error occurred. Check the error log file & contact support.

Errorlog: Calpont[126444]: 58.965545 |0|0|0| E 00 CAL0000: /data/buildbot/bb-worker/debian9/mariadb-columnstore-engine/utils/rowgroup/rowgroup.h@814: assertion '0' failed

When removing the case when part or the bit_or, the query is working

simplified query:

select grouped_column,
case when count(distinct not_grouped_column1) = 1 then
min(not_grouped_column1)
else
count(distinct not_grouped_column1)*-1
end as not_grouped_column1,
bit_or(not_grouped_column2 )
from ( select grouped_column,not_grouped_column,not_grouped_column2 from....) subQuery

group by grouped_column