Invalid deadlock detection

After upgrading from Debian Jessie to Debian Stretch using MariaDB 10.1.32 packages from mariadb.org, we immediately started having problems with our backup software, Bacula ( www.bacula.org ) - the backup jobs are failing with this error:
Deadlock found when trying to get lock; try restarting transaction

This is happening every night for different backup jobs (probably random) and has NEVER happened before. While upgrading Debian, there was only a minor version change of Bacula (7.4.3 to 7.4.4). From my observation, error is happening for randomly for same SQL commands, sometimes after 300 seconds, sometimes after 2000 seconds of execution/waiting for locks. This is happening even after i set this:
innodb_lock_wait_timeout = 100000

I also tried upgrading to 10.2.14 and set this:
innodb_deadlock_detect = 0

Which does nothing, problem persists.