RE: DVD folders. This condition has been noted and is being investigated - a solution is available but is not ideal.
Please continue to use the 8.90.003 image as we need to investigate all potential problems. Without your input, bugs could remain undetected. This is what alpha builds are for - they are not fully working releases but a snapshot of what is to come.
Do not worry. Still on LIBREELEC v8.90.003 Alpha. Bluray with makemkv work though!