Raspberrypi/raspbian and webpage rendering help

Didn’t know where else to turn so I thought I’d come to Talk. Disclaimer: I am not a programmer.

Setup:
I built a magic mirror using a RPi3 running Raspbian and the MagicMirror2 project.

On the mirror I have a formatted google map view. I have to run it in an iframe window for MagicMirror to accept it. So I have an express-js webserver running on the rpi that hosts the .html file that has the visually formatted gmap view. The magic mirror iframe viewer points to my localhost:3000, which is the port that my express-js server runs on.

The magicmirror software used to be able to display this without issue. Then all of a sudden about a year ago, it stopped. When I access to express server port from my windows PC, the formatted gmap page displays (rpi is bound to 192.168.0.103; so pointing to 192.168.0.103:3000 fromy my pc renders the gmap server in browser.) But from my rpi, when I try and access that address, or just localhost:3000, I get a blank page with nothing rendered (although the title of the html file displays correctly: “Styled Maps - Night Mode”; it doesn’t 404.)

Any ideas what could be causing this? Did some update to rasbian (granted, I haven’t performed any system updates) nerf some CSS or HTML capabilities to where it just can’t render the .html file as formatted?

Seperately, when I try and open the .html file through Chromium on my rpi, outside of the express-js hosting server, the same thing happens - the page shows the correct title but it’s just a blank white page; if i open the html file directly from chrome on my pc it is able to render it in browser.

I tried to paste the html code in a code block here but discourse threw an error.

I’d probably start with running apt-get update and apt-get upgrade on your Pi, other than that it does sound like a rendering issue. Maybe the process to render from google has changed over the last year? See if the map apps release notes have anything perhaps

You can try looking at the console to see if there are any errors that explain this.