Levels adjustment doesn't take properly

[ToreB]

I am experiencing a really bad error when using adjustment layers "Levels" or "Brightness/Contrast": adjusting black level or contrast doesn't 'take' properly (only very weakly) when pressing "merge" or flattening the image. There is a big difference between how Affinity Photo previews the adjustment and how it actually will come to look when activating it by merging down the adjustment layer or flattening the image in the document menu, as can be seen in these screen shots:
1. Image freshly loaded into Photo.
2. Adjustment made with "Levels" adjustment layer to boost darkness contrast.
3. When pressing "Merge" the adjustment contrast level weakens considerably and image almost returns to initial state.

Affinity Photo 1.8.3.641

[Old Bruce]

2 hours ago, ToreB said:

There is a big difference between how Affinity Photo previews the adjustment and how it actually will come to look when activating it by merging down the adjustment layer or flattening the image in the document menu ...

I think this is due to viewing and making the adjustment at 23% instead of 100%. Think of it as the effect is multiplied by 4 because of the zoom being a quarter, this is an inaccurate description and is just something that I keep in my head when making any kind of adjustment or applying a filter.