Trouble with evaluateJavascript

I’m trying to sign in to a site with Scriptable. This site

I can get it to load in a webview and present but if i evalute javascript against it then it never loads when I try to present the webview and nothing returns from the javascript, even when all i put is var text = 1;

Does anyone have an idea why I can’t seem to evaluate javascript on this page?

Perhaps you could share your script? It seems to be fine for me.