Same problem. WebView2 requires a user data folder, by default, it is <MyDocuments>\PHPMaker2026\WebView2 which is writable normally. But in your coase it is also redirected by OneDrive and leading to the same problem. It is not the same folder as the backup folder.
If possible, you can try turn off backup for the Documents folder from your OneDrive for the time being to avoid such problems, before we can handle like the backup folder from next minor upgrade.