Its not a bug. To easily get the color text you want for a block, put the page in edit mode, click the block with the color issue, and in color or font color (depends on version) select a color, make sure you press the littl ok button on color selector than press save. Your new color will now show as the text for that block.

So page in edit mode, click form block, select color, pick white, press ok, press save, publish your edits.

I am running 5.5.0 I think, and am editing it now.

I only see Edit and Option as options for changing font, but there is no mention of font.

I can only edit the question.

Any other way?

Click on the form block>> select 'Design'>> You'll see the 'Block Styles' interface>> Change the font colour there.

thanks, it's working now

You're welcome.