【反馈】使离线可用无法使用

【反馈】使离线可用无法使用

v4.2.0版本使离线可用功能，可以离线下载，但是在没网络的环境下没办法访问二级文件夹，导致实际无法离线使用。

离线环境下进入二级文件夹的截图

完成离线可用的截图

v3版本时，离线可用同时会保证已经打开过的文件夹离线也可以打开，这样在离线环境下已经缓存的文件可以正常读取。但是在v4中离线完全无法读取已经在在线环境下打开过的文件夹。

Start by reproducing the offline behavior described for v4.2.0: downloaded content cannot open second-level folders or previously opened folders without a network connection. Compare it with the v3 behavior described in the report, using the attached screenshots as reference; done means cached folders and files can be opened offline.

Written by the indexing model from the issue text.