Thanks for the temporary fix. I was also encountering this problem, I’m not sure what caused it (other than updating all plugins and WordPress!)
Apologies, I’m an idiot.
I swear when I tried this before I had a <span> around the <input>, but wrapping it in a label means it’s like this:
<label>
<input />
<span></span>
</label>
So I can style the CSS how I intended. Sorry!