I'm not seeing this issue with the default font on my machine (Cantarell), but you can play around with Options>Tree & View>Select Font, maybe install a complete font package like Google Noto Sans or something.
I've been slow to get back to this. But I have now tried quite of number of different fonts and the regular text changes to the selected font, but the check marks always stay as the same incorrect large splodge. I appear to have the Noto package of fonts already installed, but that doesn't work either - it only affects the normal text.
I wonder if a different "symbol" font is explicitly used for the check mark glyph, and that is a font you have installed, but I do not??
