Selecting the transparency swatch for text color in the color picker sets the font color to white.
The bug has two parts:
1. the font color is not changed to transparent.
2. the font color is changed to white.
I have seen similar reports for earlier versions and seen the response from the development team that setting font color to transparent is not supported.
This bug report is based on the fact that the font color is changed from the current color to white. If the the transparent swatch is not supported for text color then the text color should not change when the transparent swatch is selected. The transparent swatch should be a dead square, it should not have any effect.