I found the cause using the Android ADB shell function. I had uploaded a series of test files to the emulated device using a script I had developed. When I listed the files using the shell, I noticed that group access was only 'r' - readable. Changing the group access to 'rw' with the following command in the ADB shell solved my problem.

chmod g+w *

Obviously there has been some internal change in the Android OS between API 34 and API 35 that has resulted in my problem.