Lazyloaded images are not rendered on Firefox

[pzheng64]

https://fourwheelcampers.com/stagingwp/model/project-m/

If you look at Grid Gallery section. you can see no images are loaded on Firefox while they work fine on Google Chrome.
The point is that src attribute of tag is inline SVG to show empty image and data-src contains the actual image source URL.

I'd appreciate if you could fix this asap.

I tried both v3.8.0 and v3.8.1, but no luck.