Images not staying up for more than a few seconds, how so?

Anyone have an idea how my photos aren't staying up in the spotted thread please? I'm doing it in the right way as it worked before, that's to say using the along with its end tag and posting the image url between, selecting 800x480 and cropping the urls back to the .jpg without the extra borst after that file type identifier. I've received a couple of PMs from a kind member who explained that they'd been taken down because of having shewn registration plates that were "subject to disproportionate emphasis" in the images but this morning, I posted some side-on shots of my recent crop and they too went the journey after I'd posted, left the thread, then re-entered to see whether they too had been taken down immediately. I must emphasise, hopefully in an appropriately proportionate way, that these images were seen after I'd posted, but had in each case vanished by the time I went back, leaving only the [/img] tags to indicate where the pics had been.

I'm assuming that this is some form of glitch because the same images, posted the same way on autoshite, the xB club site and the eBay members' old car group boards, have all worked just fine.

If it helps, my computer is a mid 12 Macbook Pro A1278 model, built in March last year and running an up to date Mint (18.1), though that shouldn't matter as I've also uploaded from another distro and that (Android) showed the same symptom. Images are hosted on flickR and do not contain my coordinates or the exif data as I remove these from the jpg when embedding in public fora.

Any ideas?

Thanks in advance,

John.