0.98.1: Displayed incorrectly in grayscale TIF

[Mapaler]

XnView: MP 0.98.1 - 64-bit
OS: Windows 10 - 64-bit

Effect: A black bar appears

To reproduce:

1. Use any white-edged image, converted into a 256-order Grayscale image.
2. You can use Batch Convert, or exports. And can be converted to TIF or PNG.
   • 图像 54.png
   • 图像 55.png
3. Open conversion results and zoom to less than 100%。
4. A black bar appears at the bottom.
   图像 56.png

Also have this problem with grayscale images generated by IrfanView.
So this should be a display problem, not a data problem.

The grayscale images with this display problem

Test.zip

[xnview]

right, i can reproduce with bilinear scaling