Large portions of map disapearing

So I am having a huge problem and cannot find what to do.  I uploaded a map I created, it is a single image that is well under the file size limits, I put it on the background layer to serve as the map for the next session I am running.  If I zoom in very much at all then a sizable chunk of the map just disappears, I tried adjusting the map size a little,  I tried rotating the map to be more vertical instead of horizontal and the same section on the map disappeared even though again this is a single image. I did a web search on this issue and could not find any fixes and as I do not have long before my next session I am panicking about how the heck I can run any maps if a single image isn't even safe to use.

Have you tried isolating possible causes? Sometimes going through the troubleshooting steps can show where an issue lies. They are posted at the end. Also, you could try cutting your map into two pieces and assembling them on screen. Could you please carefully work through these steps of our guide to  Solving Technical Issues ? Step 1: Make sure to use the right browser Please check if these issues persist when using both Chrome  and  Firefox. Step 2: Ensure that there are no extensions/addons interfering with Roll20 Please disable  all  add-ons/extensions. Step 3: Clear your cache If none of the above succeeds, please thoroughly work through  Step 4 .  (Don't forget the complete Console Log!)

I only use firefox for one, I do not have any extensions or addons. it happened with one jpeg image, always on the same part of the image and only if I zoomed in past 50%. the image was a dungeon I map using the program Dungeondraft, then exported into a jpeg, then compressed to reduce it to the file sizes roll20 allow, just to be safe I even dropped it all the way under 4 megabytes just to be absolutely sure it wouldn't be taxing the system