You can use ES2.Exists to determine if your save exists at a given path. So if you have access to a device which has this issue, you should be able to use it with your filename appended to the paths above to see if they exist. Note you will need to replace mycompany, mygame and the uuid with your own where applicable.
You might also want to check if the original location was on the SD card, as Unity might be suddenly forcing it to use internal storage even when you've told it to use external storage. The location of this is:
You should then be able to use ES2.Rename to change the path of the old file to the new Application.persistentDataPath./storage/sdcard0/Android/data/com.<companyname>.<productname>/files
All the best,
Joel