PNG transparency of cover file lost after data hiding, and loss of image quality in digital watermarking

[poise0]

I'm using Windows, tested with both openstego-0.8.6.zip, Setup-OpenStego-0.8.6.exe, and openstego-0.7.4.zip.
Any cover file with transparency seems to lose its transparency after data hiding. I used a simple .txt file as the message file.

Image used:

Output file:

Digital watermarking also gives error code: Image cannot be encoded with compression type BI_RGB) when using images with transparency. The image quality also decreases substantially with artifacts in the output using an opaque image, and the signature trength (via verification) is low (38%).

Image used:

Output watermarked file:

I have searched previous issues for image quality but did not find an .ini file for changing image compression settings.