I tried replicating your bug, created a vault with 716 entries, including attachements. Synced it with OneDrive. Exported without issues.
So my guess is, maybe your vault file is somehow corrupted? When you say, you can reproduce the bug on every device - have you tried setting up a new vault and copying all your entries into the new one, exporting it? I know this is not a good procedure, but it might help you in the long run?