I just fired up the mobile version for the first time in a month or so. Also the first time since migrating my YNAB 4 budget. I noticed that all my transaction dates are one day earlier than those on the computer interface. This may be the same error you discussed on the blog, I'm not sure. I added a transaction on my phone dated 11/23 and it showed up on the computer correctly as 11/23. Then I deleted it and added it on the computer. The transaction on my phone is now dated 11/22.
Your mobile version of the app is out of date, make sure to update it. You may just need to refresh the page. If that doesn't work, clear your cache for the site and try again. :)
Thanks!