I tested changing the skins in the demo-version of caustic. After doing that, the font changed to big black blocks, no matter which skin I applied. Also changing to the default skin didn't help. The letters of the Option menu are clear visible. Only the font of the synths and the dialog boxes are strucked. If more Info is needed, I would like to help.
Samsung Galaxy Tab A. (2016)
Android v. 7.0