Issues Sending Email from Form

I have struggled for several days now to create a ‘Contact’ page where someone enters their email and message in a form, then the form is submitted and it sends an email to me with the information. I’ve tried using Contact Form 7 and briefly using a few other plugins. Finally I decided to just do it by hand outside of wordpress, just linking to it from the other pages. However, even by hand the email does not send. This is code that was working well on another server. It does work in one specific case, outlined below:

It works ONLY when I am running chrome with the developer tools open and the option ‘Disable cache (while DevTools is open)’ selected. If I do that, the form works perfectly and I receive the email immediately.

If I load the page normally, or even do a hard refresh but don’t disable the cache, the email doesn’t send. These findings are true for both Contact Form 7 and my own form.

It’s very strange and I can’t find any leads to help me debug the issue, especially since it does work when the cache is off. It seems ridiculous that I’m spending this much time to get a simple form working. The specific page is https://www.sensingplaces.com/contact-us/. Any help or leads would be greatly appreciated.