Hello badhandoek & zooster,
this is correct, there is an issue with the Insider Previews.
Please have a look here for more information and a workaround:
https://www.boxcryptor.com/en/help/quickstart/windows/#install-boxcryptor
If the workaround doesn't work for you, you can use the "Portable" version to access your files.
On the other hand, Classic isn't supported anymore and we don't suggest to use it under Windows10:
https://www.boxcryptor.com/en/help/faq-and-troubleshooting/windows/#download-boxcryptor-classic
Best regards,
Yasmin