macOS Mojave 10.14.6
InDesign 15.1 & 15.1.1

When a document is open, some of the fonts will not visibly load. However when you go to Type > Find/Replace it shows there are no font issues. Preflight is green and all fonts are listed as "OK". We then immediately close the document and reopen it everything looks fine. When the same document is opened hours later the problem repeats itself.

Notes:
• It appears that fonts loaded from the Document Folder ONLY are OK.
• Fonts that are loaded simultaneously in Font Book and the Document Fonts folder fail to display correctly.
• We do not use Adobe fonts.
• Fonts are typically either in Font Book, and/or they are in the Document Fonts folder for most of our jobs.
• One of the InDesign files experiencing this bug was created in 2019.
• Making a Press PDF while the fonts are bugged out creates a PDF that displays everything properly.
• If I try to print the InDesign file with this font bug, the document fails to print and gives me the following error: “Printing Error: The Adobe Print Engine has failed to output your data due to an unknown problem.”

Things I've tried:

• Clearing font caches in macOS
• Clearing the macOS Library Caches
• Deleting the AdobeFnt.lst file in the Documents fonts folder
• Moving Document fonts folder elsewhere, open the file, then move doc fonts back.
• Repackaging the job
• Turning off the Adobe Fonts service located in the Creative Cloud app
• Leaving the document open for over an hour to see if fonts would load on its own.

Bug replication:

In some instances, moving the Document Fonts folder to the desktop, opening the file, close it and moving the Document Fonts folder back to its original location would trigger this bug. But it doesn’t work all the time. The steps below are more consistent with replicating the bug.

1. Delete the AdobeFont22.lst from the Document Fonts folder.
2. Open the document - fonts are broken (even though they are also loaded in the system). Preflight is green.
3. Close document.
4. Open the document again and the fonts load properly.

We did not encounter this bug until 15.1.