@PitaJ @archprateek @azeus Same issue here. After submitting the original post, the event code tags are changed to "event-invalid". When editing the post, I can either manually edit the tags to "event", or use the composer button to edit the event. In both cases the event shows up as fixed.
I've also posted a new issue here:
My guessing is that those issues are related to date formatting and/or user locale, which explains why they don't show up reliably on all setups.