Unable to insert certain row

Hi! I have trouble to insert (statement in attachment) one row to the table:

CREATE TABLE `text` (
`old_id` int(10) unsigned DEFAULT NULL COMMENT 'autoincrement=1',
`old_text` mediumblob DEFAULT NULL,
`old_flags` tinyblob DEFAULT NULL
) ENGINE=Columnstore DEFAULT CHARSET=utf8

The insert process appears in process list with the Update state and lasts here forever. I can't see any progress.

I checked logs in /var/logs/mariadb/columnstore but can't see anything helpful.

What I found weird is that if I remove the last few characters from 2nd field then the insert works properly. Additionally if I add few more characters it also works. Unfortunately I have no idea what is the cause. Thank you in advance for your time.