MariaDB 10.1.21 silently skipping INSERTs

Since upgrading to MariaDB 10.1.21, INSERTs in a certain table are silently skipped.

E.g., the following query:

INSERT INTO supplierItems (itemId, supplierId, supplierItemId) VALUES (9788711721780, 99, 1234567890);                        

Gives "0 rows affected" as a result:

Query OK, 0 rows affected (0.00 sec)

And the inserted row is nowhere to be found:

SELECT * FROM supplierItems WHERE supplierId = 99 AND itemId = 1234567890;
Empty set (0.01 sec)

Glancing over the release notes (https://mariadb.com/kb/en/mariadb/mariadb-10121-release-notes/), I suspected this to have something to do with the table using compressed row format. However, converting the table to compact row format did not resolve the issue.

While the issue persists, it unfortunately isn't reproducible by creating an identical table in another database.

No warnings or errors appear in the client or the server log.

Any clues what might be at play, or how to go about debugging this?