Thanks for your advice. I agree that the simplest solution would be to choose a more suitable cloud provider.
But I'm mainly using Onedrive at the moment so I'd like to be able to sync with it without issues.
I started a new sync without filename & filepath encryption, it looks like it's working.
This issue with Onedrive might be linked with obfuscation as I have no issues with my other crypt remote with standard filename encryption.