When specifying logrt skip to item key, Agent lost the log.

procedure
---------
1.specify logrt skip to item key.
(a)logrt["test.*.log",ERR,,,skip]
(b)logrt["test.*.log",INFO,,,skip]
2.start agent.
3.write INFO string to logfile. (file size of logfile is not 0.)
4.wait for INFO data to be displayed by a history screen.
5.stop agent.
6.write ERR string to logfile.
7.start agent.
8.agent skipped written ERR string.

The agent receive 0 of lastlogsize of (a) from the server at the time of the second start (No.7), because agent has not sent log data of item(a) which results in the server doesn't receive lastlogsize data from agent.
Therefore the agent skipped written ERR string log.

However, We think it is lost ERR string, because of the agent starts once.

Whether this is restrictions or is it a bug?

Thank you.