Why does my form disappear from my website at certain browser widths, and how can I prevent this?

If you check your form using the direct URL, you will notice it works properly on every device: https://www.jotformpro.com/form/82256956489980 

JotForm forms are mobile responsive by default and this remains when the forms are embedded. 

However, I have been checking your web site and it seems like it works with some sort of breakpoints: 

So what happens  is that your site hides and shows content depending on the screen size. Unfortunately, this is not something JotForm has control so you will need to further check this with your website builder support or the web developer that worked on your site. 

Thanks. 

Thank you for your help. I did a bit of troubleshooting, and found that you are correct -- it was indeed the breakpoints that were causing the problem. Easy fix once I knew what to look for. :)
NOTE to fellow Adobe Muse users: if you're setting up a page using breakpoints, and you want to embed a JotForm form, it may become invisible at below a certain minimum width -- even though it still previews fine in Muse. Kudos to Kevin_G for the quick and helpful response!