I'm still working on it, but I think the issue is that the Canvas component always asks for write permission, which is problematic in Android 11 because the permission is gone. Effectively, the Android system reports the permission as being denied, and so the Save block signals a failure due to the lack of permission when in fact it should proceed as normal. I'm going through and auditing every component that references the WRITE_EXTERNAL_STORAGE permission to see if this is a problem elsewhere as well.