So for example, I opened this page

https://www.copart.com/lot/44813780/2020-volkswagen-gti-autobahn-tn-nashville

and clicked the image, and an enlargement appears to the right. As I move around over the main image, the enlargement shows a different area of the image.

That isn't working on your Firefox? Hmm, not sure why.

If a site is generally known to work in Firefox, these are standard suggestions to try when it stops working normally:

Double-check content blockers: Firefox's Tracking Protection feature, and extensions that counter ads and tracking, may break websites that embed third party content (meaning, from a secondary server).

(A) The shield icon toward the left end of the address bar usually turns a bit purplish when content is blocked. Click the icon to learn more or make an exception. See: Enhanced Tracking Protection in Firefox for desktop.

(B) Extensions such as Adblock Plus, Blur, Disconnect, DuckDuckGo Privacy Essentials, Ghostery, NoScript, Privacy Badger, uBlock Origin or uMatrix usually provide a toolbar button to manage blocked content in a page. There may or may not be a number on the icon indicating the number of blocked items; you sometimes need to click the button to see what's going on and test whether you need to make an exception for this site.

Cache and Cookies: When you have a problem with one particular site, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site.

(1) Clear Firefox's Cache

See: How to clear the Firefox cache

If you have a large hard drive, this might take a few minutes.

(2) Remove the site's cookies (save any pending work first). While viewing a page on the site, click the lock icon at the left end of the address bar. After a moment, a "Clear Cookies and Site Data" button should appear at the bottom. Go ahead and click that.

In the dialog that opens, you will see one or more matches to the current address so you can remove the site's cookies individually without affecting other sites.

Then try reloading the page. Does that help?

Testing in Firefox's Safe Mode: In its Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" Help > Restart with Add-ons Disabled
• (menu bar) Help menu > Restart with Add-ons Disabled

and OK the restart. A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

If Firefox is not running: Hold down the Shift key when starting Firefox. (On Mac, hold down the option/alt key instead of the Shift key.) A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement?

Doesn't work for me as well properly. I need to make the Firefox window quite wide (1184px for the body fails, 1185px works) and refresh the page to make the zoom cursor appear. Once it appears then i can make the window smaller, but a refresh will disable the zoom once again, sometimes I see a short flash if the mouse pointer is over the image. So it looks that something with the JavaScript isn't working properly in Firefox.

Oops, I didn't think of that (tested using a maximized window on Full HD monitor).

On mine, the cut-off seems to be a perceived page width of 1200 pixels. By perceived I mean taking zoom into account. So if your window is physically about 1087 pixels wide and you zoom out to 90%, then reload the page, the click to zoom feature is enabled because the inner width now computes to 1200 pixels.

On Google Chrome 90, the zoom trick doesn't seem to work, so my window needs to be 1216 or more pixels wide to enable click to zoom.

Bingo, the default zoom was set to 170%, I did try to make some changes to this initially however when I set it to 100% and refreshed the screen it was working properly.

Thanks, Eric