QT5 on RPi (eglfs) shows rectangles instead of non-ascii characters

[Zork]

I have a Yocto based layer for QT/QML development for RaspberryPI 3 - meta-rpi-qml

It is based on Dunfell (Yocto 3.1), QT 5.14.1. I compiled image, sdk and setup QtCreator for cross-compilation and remote debugging.

I created simple 'Hello world' app and I am unable to display non-ascii characters. I see rectangles instead of polish characters ś,ł etc...

QWidget.fontInfo().family() returns "BitVera Sans" - this font has support for polish characters.
When I run my test app on desktop all characters are shown correctly.

I think that I am missing something in my layer but I do not know where to search.

I would be grateful for any pointers.

[Zork]

That was really a bizarre bug.

My image had only one font: Bitstream Vera.
Adding another font (fore example FreeSans.ttf) fixed unicode display with Vera.

If Vera is the only one then unicode chars are broken. Looks like a bug in freetype or Qt?