Issue with Product Search Widget

I'm using Flexmarket theme - I'm using their Product Search Widget Plugin. With this plugin, I have added it to my sidebar on my homepage and stores within my network.

Now - I am having issues with the Search Results after I entered a query.

For example, on I can search "Pink LED". Something comes up, but it's only for a split second. And then it goes away.

My server provider (WPEngine) said it's not a caching issue. This is what they said:

I'm seeing the following error in the console:

Failed to load resource: the server responded with a status of 404 (Not Found)

for the url

Please let me know how I can fix this!