Thanks for the replies.

The problem is present in other Chromium-based browsers, such as Edge and Chrome, too. It's also there in Firefox.

I'm only working on the base layer.

As my illustrations at 4.59pm show, 'Repel text under' works absolutely fine within XWDP itself. (If I move an image around, the text auto-adjusts to flow around it). The problem only occurs when I preview or export my website, when XWDP produces a website where the 'Repel text under' command has been totally ignored for every image that it's been applied to.

I've exported what I've done on the design so far as an XAR file, which I attach here.
index.xar

If it loads the same for you as it does for me, everything in the 'Gallery' page displays correctly. (i.e. with the text repelled by the images). However, when previewing the site in a browser, the images overlay the text.

Ideas, anyone?