Hey there! Let's figure out why your custom TrueType fonts aren't showing up in LibreOfficePortable— I've dealt with similar portable app font quirks before, so here are some practical checks to run through:

• Double-check the font folder path
  Sometimes the portable version's font directory can be easy to mix up. Make sure you're placing your .ttf/.ttc files in LibreOfficePortable\Data\settings\user\fonts— that's the official folder where the add_fonts_here.txt should live. If you dropped them in a different "fonts" folder elsewhere in the portable directory, LibreOffice won't pick them up.

• Verify your font files are intact
  Corrupted font files won't load, no matter where you put them. Try opening the fonts in your system's default font viewer (like Windows Font Viewer) to confirm they display properly. If they look garbled or fail to open, you'll need to grab a fresh copy of the fonts.

• Ensure a full restart (no background processes left)
  A quick close-and-reopen might not cut it— sometimes LibreOffice leaves background processes running that keep old font data cached. Open your task manager, end every process with "LibreOffice" in the name, then launch the portable app again.

• Check LibreOffice's font settings
  Open LibreOfficePortable, go to 工具 > 选项 > LibreOffice > 字体. Look for options like "使用系统字体" (Use system fonts) — if this is enabled, it might prioritize your system's fonts over the portable ones. Try unchecking it, applying the change, and restarting.

• Manually scan for new fonts
  Some portable builds don't auto-scan for new fonts right away. In the same 字体 settings menu, look for a button like "字体设置" (Font Settings) or "添加字体路径" (Add font path). Add the folder where you placed your custom fonts, then hit the "扫描字体" (Scan fonts) button. Restart the app after this.

• Check folder permissions
  If your LibreOfficePortable folder is stored in a restricted location (like C:\Program Files or a protected system folder), the app might not have permission to read the new fonts. Move the entire portable folder to your desktop or a non-system drive (like D:) and test again.

备注：内容来源于stack exchange，提问作者U. Windl