All files exported to pdf have same syntax issue after one 'failed to create pdf' error

I'm suddenly running into an error with every file I try to export from InDesign to pdf. Regardless of the file -- existing file that's big/complex, new file with literally one sentence in a text frame, saved as indd, saved as idml -- when I export to pdf, my pdf has the following syntax issue:

General File Format Error: Key missing though required by other key

• The key /LastModified must be present when key /Pieceinfo is used

• The key /First must be present when key /Count is used

The whole thing started after an export failed (i.e., I got a "failed to create pdf" message). I just backed out, restarted and tried again. Now I can export pdfs but they're all perceived as corrupt b/c of the syntax error. The file preflight in InDesign shows no errors, but the files are perceived as corrupt. When I pull them up in Acrobat and check tools, preflight, I see the reported errors.

I've uninstalled and reinstalled and cleaned the registry in between but the problem remains, for files created both before and after the reinstall. I also ran a disk check but Windows 10 says everything's fine. Can someone help me figure out how to fix this?