Just for testing I installed Ubuntu 16.10 32bit in a virtual machine.
I found that it is something to do with the word "[space]Greek" in the font family name.
It worked ok if it was "SBL[space]test", so that proves it is not a space issue.
The part I don't understand is that SBL Greek font displays correctly in the Bible view, but does not for the popup.
On Windows 10 there is not an issue in either place, figure that one out.
I used a font creator to edit the internal details as shown. The popup is now ok.
0003 Jon theWord_2017-02-07_180411.png [ 21.14 KiB | Viewed 145 times ]
0004 Jon theWord_2017-02-07_180522.png [ 63.2 KiB | Viewed 145 times ]