非常抱歉！我认为这是最近出现的一个回归问题（过去几周引入的新错误）。这里有几种变通方法，应该能让它正常工作：
1. 尝试在“正文”选项卡中关闭“防止孤行单词”，看看空格是否会恢复：
2. 如果那样不起作用，请将以下行添加到 Advanced --> ptxprint-mods.tex 文件中：
\def\BookChapSeparator{\ }
Our apologies! I believe that this is a recent regression (a new bug introduced in the last few weeks). There are a couple of work-arounds that should get it working properly:
1. See if turning off "Prevent Orphan Words" on the Body tab brings the space back:
2. But if that doesn't work, then add this line to the Advanced --> ptxprint-mods.tex file:
\def\BookChapSeparator{\ }
机器翻译自 English
