Options not Saving

This feels like a bug in the plugin to me.

I can assure you there has been no bug with saving options for the plugin for at least 10 years now. Just check the forum for activity. ??

What you may be facing is a plugin conflict. Sometimes, plugins or themes tend to include JavaScript improperly, by having them on admin pages of other plugins, or by including a version of JQuery not supported by WP. That can cause those plugins’ settings to fail. You will need to deactivate all your plugins and try to save the options after that, then reactivate them one by one to find which one is conflicting. If, with all plugins deactivated, your options still don’t save, you might have a conflict with your theme. In that case try switching to a default theme and see if the options go through.

There weren’t any javascript or PHP errors appearing in logs that I could find. This makes me wonder exactly what javascript could get in the way, when the javascript console showed no errors.

I tried on a blank WP install, and as you expected, that did work. The interesting thing is that I could then copy the photonic_options row from the blank WP’s options table to the live one, and all stayed in place, including doing the authentication step on the live site and the plugin could then save the refresh token for itself.

So perhaps something is awry with your plugin’s compatibility with something else on my site, but at least I could use a blank Local WP install as a workaround to get it to work.

There doesn’t have to be an error. Something might just be capturing the click, but without an attached action. E.g. the other plugin might be looking for a button click, but its internal logic might be checking for a specific attribute on the button to have a specific value, to trigger some action, and upon not finding it, it might simply be failing silently.