SSD1306 Monochrome possible theme issues

Context

For A project I am using an ESP32 with an SSD1306 Monochrome 128x64 Display. As a good starting point I am using an example from ESP-IDF. This works fine and is already configured to work with the display. Added some physical button controls and added piezo feedback, but I encountered some issues.

The situation

Labels show up fine, but a button does not show up, when I add them with a label. I assume it has something to do with the styling. This also goes for other widgets that miss neccesary styling, like scrollbars, panels,

So what I tried was checking the documentation about styling. And tried out setting some text colors (white or black), border colors, etc. But I got nothing. Labels work fine though, but can’t seem to set a border color or anything either.

Other things I found

I also found a post about setting a monochrome theme, which I (think) did by adding #define LV_THEME_DEFAULT_INIT lv_theme_mono_init at the top of my code (since the example from espressif declares configurations in the sdkconfig file.).

Any Input would be appreciated.