Strange white bloom?

[Bananaj]

I recently painted my dining room using Dulux Roasted Red Matt Emulsion. An odd white bloom has appeared roughly a meter square halfway down one wall. It doesn't wash or wipe off and hasn't spread. I painted another couple of coats, no change. Tried Zinsser bin primer-sealer &stain killer, the spray version, gave it two coats and then two coats of paint, still there. Just tried Polycell one coat Damp Seal (as I'd run out of ideas!) and another coat of paint and it's still there. It's an internal wall, previously magnolia from when we moved in. The patch is in the middle so nothing rising or dripping down. Any ideas what it might be and how I can remedy it please. I tried taking a photo but it doesn't show.

 

[footprints]

Now maybe this sounds silly but are you sure it's not a shadow or a reflection on the wall from a window or mirror?

 

[Bananaj]

Ha ha ha!! Just enjoyed a real good laugh. Saying that, I had the same thought initially and so ignored it for a week or so before I started re painting for England. It's there regardless of sun and cloud, curtains open and shut etc.

 

[footprints]

Sorry you seem to have done all the things I would suggest, so I'm out of ideas unless you are living next to a rift in time and space!

 

[Bananaj]

Thanks anyway! Thought I'd ask before trying anything else on the market. Guess I could always paint it white.