1) Addons are being updated by authors but are not showing on the curse app as an update available. Few notible addons are GTFO, Sorha Quest Log, Deja Character Stats, and all of Alar's addons. Either curse.com is having a breaking bug, wowace, or curseforge are not syncing, or the curse app is not registering updates. Take GTFO for example, it shows a new release 8 hours ago from the time of this writing but nothing is showing on the app.
2) curse.com is showing new releases but when going to the addon's project page and looking at files, they are not showing new files.
3) The curse app is not showing the latest release when browsing all apps. This is a longer running issue. You do not show or have an option to view addons by release status. It means that if you go to browse for an addon, it will only show the release version. The curse.com page on the other hand, shows the latest update regardless of release designation.
Here is what I mean about the update time discrepancies:
It looks like the curse app is polling from either wowace or curseforge's last update but curse.com is polling from the packager database?