Notification snapshots sometimes don't show in notification

I am coming across an issue whereby snapshots images, which are sent as part of notifications to a group of devices, do not load randomly. This happens mostly when not on the local network although it does work some of the time when not local. I have turned off Cloudflare caching for HA to check if this was the cause - it wasn’t. The only thing I can think of is that when the notification is delivered there isn’t enough internet connection to load the image. Is this plausible and if so is there a way to overcome this?

Many thanks in advance.