We've had a few reports of customers struggling with this latest Dymo update. If you are having any problems, we've found the below options helpful for troubleshooting.
I'm receiving a 400 error - First, try to print directly from the newly installed Dymo software, then try Check-Ins again. If you're still receiving an error, right click on the widget and click "stop service." You'll need to restart your browser, but that should force the older version of the plugin to take priority. This won't work with Chrome or newer browsers anymore, but should work with the setup you had before (in most cases, Firefox).
My computer can't install the latest Dymo version - The latest update requires OSX 10.10 or greater. Some older versions of Windows might not work either. If you are on an older version, you can still use the same setup that you did last week (in most cases, Firefox), but it won't be compatible with Chrome, or any other newer browsers. Also, Firefox is planning on dropping support for this within the year. Check-Ins will work for you in the short term, with the same setup you had before, but you will need to update your devices soon, if you want to continue using Dymo with Check-Ins.
If you fall into the first category, we'd love to get some more information from you within the next week so we can get the widget working soon. Please contact us at firstname.lastname@example.org with some additional details so we can followup with you!