I have encountered a strange behavior/inconsistency with how MariaDB is working with large values of BIGINT UNSIGNED. It appears that if BIGINT UNSIGNED is used and a value is larger than 9223372036854775807 (max value of BIGINT SIGNED) insert of rows with such values can fail under unknown conditions. It plagues transactions mainly, but I did have 1 case outside of a transaction as well.
Code samples and more details can be checked in https://dba.stackexchange.com/questions/293791/missing-an-inserted-row
I will be trying to get a consistent way to replicate this and update both StackExchange and this bug report as soon as I find any new info.