I can see a thumbnail of the image in the infobox at https://en.wikipedia.org/wiki/State_of_Palestine but cannot see it enlarged in media viewer.

When I click on the thumbnail in the infobox, it opens the page
https://en.wikipedia.org/wiki/File:State_of_Palestine_(orthographic_projection).svg
This just shows a tiny broken image icon, with the text:
File:State of Palestine (orthographic projection).svg
Size of this PNG preview of this SVG file: 550 × 550 pixels. Other resolutions: 240 × 240 pixels | 480 × 480 pixels | 600 × 600 pixels | 768 × 768 pixels | 1,024 × 1,024 pixels.
Original file ‎(SVG file, nominally 550 × 550 pixels, file size: 1.45 MB)

Bypassing cache does not resolve the problem.
Ha! It loads OK in Safari.
It also loads OK in a normal Chrome session. I was using an incognito session.
Incognito session still reports:
Sorry, the file cannot be displayed. There seems to be a technical issue. You can retry or report the issue if it persists. Error: could not load image from https://upload.wikimedia.org/wikipedia/commons/thumb/a/ad/State_of_Palestine_%28orthographic_projection%29.svg/550px-State_of_Palestine_%28orthographic_projection%29.svg.png
(hope I got that right, as I had to manually retype it)

Do you use any add-ons / extensions in your primary browser which might block this?

Nnn... well blow me over, there was an extension called Cookyummy, supposed to keep the browser awake, now outlawed by Chrome. I removed it. After that, all is well.

I have been having issues displaying images for some time. Hopefully that will fix it.

There remains an issue of displaying mathematical formulae, which appear momentarily then vanish (in incognito sessions). This is presumably unrelated.

There remains an issue of displaying mathematical formulae, which appear momentarily then vanish (in incognito sessions).

That probably means the on-page thumbnail is used as a placeholder, and then replaced with the real image, which does not show up, but does not give a HTTP error either (otherwise there would be an error page). I'm a but surprised that MediaViewer works at all with Math formulas, that was never intended...