I am trying to view an epub file I created in Kindle Previewer 3
but the only view option choice is E-Reader. Any ideas on what the problem may be? There is no phone or tablet option

Thanks for your help
You can only change the device type when you have a book open. Is your book currently open in the Previewer?
Thanks for your reply
The ebook is open in the Kindle previewer but the only viewing option is
E-Reader I cannot change it to tablet or phone view options because those options aren't available.
This problem just started today. The viewer always allowed me to switch to all three viewing options
Use a tablet, phone and an eInk ereader (At least a Kindle and Kobo). Use a variety of apps on phone & tablet that respect css. Lithium for epub on Android and Kindle for azw3.

I also test on an old Kindle that can't do azw3/KF8.
Have you tried rebooting? If that doesn’t work perhaps uninstalling and reinstalling might fix it.