OneDrive synchronizing does not allow the filenames generated for OpenOffice lock-files ("Illegal characters", see explanation below). This will generate a message from the OneDrive client whenever you open a file from your synchronized OneDrive folder, and
the "cannot sync" badge you describe will appear on the lock file icon.
This "lock failure" implies that concurrent access to a OneDrive folder from multiple nodes (separate computers, physical or virtual), is not reliable when you use OpenOffice. You may get "update conflicts" if one file is edited from two nodes concurrently. Normally your lock files are hidden and the document file will sync fine, so you should not see the badge (only the status message from the sync client driver). It will display if you have chosen to view hidden files, and if the cause is a different one (see list below).
LibreOffice is said to have better Microsoft support, but I don't know whether LibreOffice supports other locking mechanisms which work over OneDrive connections.
Other typical situations when you get the "cannot sync" badge:
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Too large files (single file >4GB). I believe that you can upload those manually to OneDrive by logging in the O365 website. They will not synchronize through the OneDrive client driver.
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Too long path. The pathname, including filename+extension, must not exceed 256 characters.
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Illegal characters. Typically you may have downloaded files from elsewhere, getting "webified names" with e.g. the "%20" token inserted for space. The percent sign, along with a few other characters, is allowed in local file names but not in the cloud storage.
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No space left. There is a limit to how much storage your files can occupy (storage space, anywhere from 5GB to 1TB, depending on your subscription) and also the number of files you can have on your drive (directory space, 20000 on personal accounts and 50000 for enterprise accounts, IIRC)