it seems that the graphics changed to V16.

There is a workaround:

1. Select your graphic
2. Goto Properties > Properties > Appearence
3. Set Background "Fillpattern": Transparent
4. Check Graphic "Transparent" checkbox
5. Set Graphic "Transparent color" to "211,211,211"

The color "211,211,211" (the background color of the graphic) is now displayed as transparent.

In the screenshot you see the workaround at the left and the original without workaround at the right side.

https://support.industry.siemens.com/forum/it/en/posts/tia-portal-v16-wincc-transparent-graphic-problem/237514