Steps do reproduce:

1) Download attached project 'SaveUnityRepro.zip' and open in Unity
2) Go to Player Settings >> Other Settings >> Write Access >> set to Internal Only
3) Build and run on a device
4) Press the 'Add 1' button several times
5) Press 'Save' button
6) In Editor, go to Player Settings >> Other Settings >> Write Access >> set to External(SDCard)
7) Build and run project on a device
8) Press 'Load' button

Expected result: Data should be loaded from Internal memory
Actual result: Check logcat 'No save data found'

Reproduced with: 5.3.6p7, 5.4.2p2, 5.5.0b10, 5.6.0a1