RDS snapshot export task does not work from Starting status

Hi, I'd like to ask a question about RDS snapshot export task.

(Here is the document of this feature.)

I use RDS snapshot export as daily batch job since last year, and it had been worked so far. From yesterday, however, the export task does not work from 'Starting' status, and there is no information more than status about that working task.

I've tried to cancel current working export task and tried to re-run the export task, but nothing had changed.

Are there anyone who have the same issue? And how to resolve about this issue?

Thanks.