Blank images on mobile when sending self-hosted image

New to RocketChat. Interested in using it with HomeAssistant, which has an integration but I’m running into a strange issue.

I’m trying to send an image, which in HASS uses this API: Post Message - Rocket.Chat Docs. Specifically the attachments->image_url portion. When I send an image it shows up just fine on the desktop/web app. And if I send an image from something like imgur or any other website it also works fine. But when I try to send an image_url that’s on my local ip address, say or even "http://mywebsite/my_dog_picture.jpg` (which is self-hosted) it shows up as blank on the mobile app. On the web/desktop client the image shows up fine.

I can upload images just fine either on mobile or on desktop and they show up just fine. It’s only when sending images via that API when the image is self-hosted. Is there some setting I’m not seeing that would allow images to show up?

Edit: just tried a couple more images and it’s NOT just limited to my self-hosted stuff. So some images work, others do not.