Checkbox-columns in table attributes and text in signatures rely on a specific unicode font that needs to be installed on the windows server.
The font needed (ARIALUNI.TTF) can be downloaded from https://www.dropbox.com/s/76nf3hgr4r6be0x/ARIALUNI.TTF?dl=0
Place the font file somewhere on the Windows Server, right-click on it and use the context menu to select “Install” or, if available, “Install for all users”.
Note: The server will need a re-boot for the font installation to take effect!