linux – Missing logs when SystemMaxUse is reached


i’m using journalctl for logging under kernel 4.9.
Now when the SystemMaxUse is reached(currently 16 MB), all new log entries are written to /var/log/journal/../system.journal but are missing after reboot. While the SystemMaxUse is not reached the log entries are kept as expected.
In my understanding, if SystemMaxUse is reached, old logs should be deleted first and the new one’s should be kept.
The journal.conf is:

Storage=persistent
#Compress=yes
#Seal=yes
#SplitMode=login
#SyncIntervalSec=5m
#RateLimitInterval=30s
#RateLimitBurst=1000
SystemMaxUse=16M
#SystemKeepFree=
#SystemMaxFileSize=
#RuntimeMaxUse=
#RuntimeKeepFree=
#RuntimeMaxFileSize=
#MaxRetentionSec=
#MaxFileSec=1month
#ForwardToSyslog=yes
#ForwardToKMsg=no
#ForwardToConsole=no
#TTYPath=/dev/console
MaxLevelStore=info
MaxLevelSyslog=info
#MaxLevelKMsg=notice
#MaxLevelConsole=info

Maybe somebody has a solution, for keeping new entries when SystemMaxUse is reached?