Adobe InDesign version: 16.0.1 x64

Platform: Windows 10, Version 20H2 (build SO 19042.685)

Problem:
Suddenly, from a couple of days, I cannot export in PDF format anymore.
When trying to export a file, I receive the message "Failed to Export PDF" (or something similar, I use the Italian version) – see image 1.

It doesn’t matter the settings in the export window, I tried almost all the combinations, but the PDF generation fails.
I can export in.jpeg, for example, but it is not useful for me.

Infos:
The same file has been successfully exported just a couple of hours before.
The only change in the tool / PC configuration was the re-installation of a font type (specifically, the Conduit ITC Pro).
I re-installed it because, even if it was correctly installed, I was not able to see the text in that specific font in InDesign.
I un-installed it and then re-installed it via the Windows settings (Control Panel > Appearance and Personalization > Fonts).
The font was not an Adobe Font.
After that, everything seemed to be solved, but I was unable to export the file in PDF.
I noticed that the font was listed three times in the “Find/replace Font” window (see image 2).

So, I replaced the font with the same one and then the list presented just one instance.
Solved! In this way, I’ve been able to export the file.

Then, I tried with another file, but I encountered the same problem with another font.
In this case, it is a font used in the header of a master page and the text is a “text variable” that I use to identify the product name.
Also in this case, the text is not displayed, even if the font is available in the font list (see image 3).

If I change the font, the text is displayed (see image 4).

The font, in this case, is an Adobe Font (see image 5).

The font is correctly “activated” and available in the Creative Cloud Desktop app (see image 6).

And also in Windows (Control Panel > Appearance and Personalization > Fonts), it is correctly displayed and recognized (see image 7).

I solved replacing the font and checking the "Redefine Style When Changing All” box, because several paragraph styles use the same font, but I’d need to use this font.
In another PC, with the same configuration, everything works well.
What can I do to solve this font issue? Why has it happened?

Thx for the support

BRs