Further to Tom’s fix…I’ve come across a case where even this doesn’t work because the PostLoad for the TextRenderComponent is called BEFORE the PostLoad for the Font (which initialises GetMaxCharHeight()).
IMHO the most robust solution is for GetMaxCharHeight to self-test and call CacheCharacterCountAndMaxCharHeight() if it’s uninitialised - but that still requires Tom’s fix to correctly set up the TextRenderComponents.