After a bit of testing, I noticed that removing ~/.config/libreoffice/4/user/TexMaths/TexMaths.cfg solves the problem. Also, this file isn't recreated, maybe it was a relic from an older version and interfering with the newer options? Maybe because of this line: FileFormat=png
I renamed ~/.config/libreoffice and reinstalled texmaths, it worked. Any idea why it wouldn't work in my old setup?
System: Ubuntu 18.04 4.15.0-70-generic LibreOffice: Version 6.3.3.2, Build ID: 1:6.3.3-0ubuntu0.18.04.1~lo1; CPU threads: 8; UI render: default; VCL: gtk3; Calc: threaded TexMaths: 0.48 Just tested on my Laptop (identical setup), there it worked. On my Laptop the options were definitely filled automatically, on my desktop I'm not sure.
Png-Bug when creating directly from text
\draw has problems with declared functions