Hi Angela,
Thanks for your updates.
To further narrow down the issue, please allow me confirm the following information:
1. Is the first time you sync files using OneDrive for Business app on your Mac?
2. Could you check if there are some invalid characters among synced files?
3. Check if the issue will persists by clicking Preference-> About-> Unlink OneDrive for Business to stop the sync , and re-sync the library.
The following characters are not supported when you sync OneDrive for Business Mac with SharePoint Online/SharePoint Server 2013:
#, %, :, ?, >, <, “, |, *
“.” — This is supported when the period is the terminating character.
Leading and trailing spaces are blocked.
The following file types are blocked at the SharePoint level:
.ascx, .asmx, .aspx, .htc, .jar, .master, .swf, .xap, .xap, .xsf, .ashx, .json, .soap, .svc and .xamlx
The following trailing substrings are also blocked (* = wildcard):
*.files
*_files
*-Dateien
*_fichiers
*_bestanden
*_file
*_archivos
*-filer
*_tiedostot
*_pliki
*_soubory
*_elemei
*_ficheiros
*_arquivos
*_dosyalar
*_datoteke
*_fitxers
*_failid
*_fails
*_bylos
*_fajlovi
*_fitxategiak
_vti_
Best Regards,
Iris He