This entry has been posted today on Simplenote’s blog:
Today we briefly released an update to Simplenote for iOS that introduced a bug. Under some circumstances, your notes could become invisible. Not actually gone, just seemingly gone…
Read the whole post by clicking on the link above. The developer confirms that the bug has already been fixed and the new app submitted to Apple for approval. We should be able to see Simplenote back in the App Store this coming Friday 3rd June.