What do you see in the developer console? (right click on screen, “inspect element”, “console”).
If you can post the errors here that should tell us the problem.
Do you maybe have the permalinks on plain?
@mvsitecreator
I can confirm the issue is with plain permalinks currently. If you go to settings/permalinks, and choose any other option than plain, it will be resolved. Alternatively you can use the below branch, it will get merged in the next release.
It appears the WP Core apiFetch method encodes custom rest api endpoints when used with plain permalinks. As a workaround for this behaviour, I’ve dropped the WP core fetch method when plain permalinks are used. It’s merged on Github, you can use the zip from there, or wait for the next update.
https://github.com/Really-Simple-Plugins/really-simple-ssl
