LibreOffice 5.4.0.3 breaks fonts on Windows

[ljfnord]

The Liberation Sans fonts and other Linux-based fonts are all rendering as Courier on Windows 10 64-bit Home under LibreOffice 5.4.0.3, despite them being available on the system. I have made sure that I’ve got OpenGL turned off, but LibreOffice just isn’t seeing the fonts. I’ve had to resort to using Windows fonts (e.g., Arial) in order to make a spreadsheet that was readable last night with Liberation Sans readable today. Please help.

Build ID: 7556cbc6811c9d992f4064ab9287069087d7f62c
CPU threads: 8; OS: Windows 6.2; UI render: default;
Locale: en-US (en_US); Calc: group

[LibreTraining]

This has happened to me when updating previous versions.
The LibreOffice update installation breaks the Windows fonts registration.
The fonts are still there in the Windows Fonts folder but, the registration is broken so Windows does not see them.
Normally Windows will automatically see any font in the Fonts folder as installed.
But LibreOffice breaks this.
You cannot use the standard Windows font browser to fix it as it does not see the fonts in the font folder.
I used a 3rd-party font tool (MainType) to reinstall the fonts properly.
You can also use an alternative file browser which will actually see the font files in the Fonts folder, and then you can click on the font files to open with the Windows font viewer, click on the install button, and will ask you something about installing here, say yes, and it will fix the font registration and it will be installed properly again.

I now keep a backup folder of all the LibreOffice fonts so I can easily reinstall them properly using MainType just in case a LibreOffice update messes them up again.

[uundh]

I am also having serious problems with font rendering. Quite every time I open a document, the fonts, which I install via NexusFont and are activated to other programs, are rendered as Courier. I didn’t find a reproducable method to get them working. Sometimes after a restart of the system, sometimes after deactivating and reactivating them, on some days I just don’t do office work because I can’t get them showing right.

[LibreTraining]

You have posted this as an answer to the original question.
Best to start a new thread.
With that said I will answer in a comment …
I have seen LibreOffice render fonts as Courier when the font installation/registration is messed-up.
You said above that the fonts are “activated” - this is not the same as installed.
It is possible to temporarily activate fonts using various font managers.
Not sure how LO is going to handle that situation.
Make sure the fonts are actually installed.