Is this by design or a bug? v. 1.7.0.135

[Silvia]

I increased the exposure a lot on purpose as I'm going for a 'high-key' type of editing of this image.  I noticed immediately that the gray wall background behind the flower turned into transparent. pixels.  I then opened in Photo 1.6 and this does not happen,, it just turns all wall pixels white.  Wondering if this is by design or a bug.  Kind of like it.  Thanks

[A_B_C]

I haven never seen this with any of my RAW files. How did you do that? Would you mind uploading an example file, Silvia? 

[MEB]

Hi Silvia,
Welcome to Affinity Forums
This is a known bug and it's caused by the Show Clipped Shadows and  Highlights functions (top right corner in Develop Persona).
Do you mind attaching a screenshot of your Mac specs (menu Apple > About this Mac) so I can check/update our report? Thank you.

[A_B_C]

(Good to know. Doesn’t happen on macOS Sierra 10.12.6., MacBook Pro, vintage, late 2011).