Understanding the issue with the save/load (Yes/No) button is the key to an easier life... and a lot less random clicking.
For whatever reason (I speculated
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)... When you load, the "YES" button interacts with the save slot 5 icon behind it.
If when the Yes/No option appears... you move the mouse around a bit without trying to click anything, you'll see the glow around the save slot behind it lights up when you're mousing over it too.
If
BOTH "save slot 5"
AND the "Yes" button are highlighted... "Yes" won't work.
If you move the mouse left, away from "save slot 5", but not so far that the Yes icon disappears - You
CAN click "Yes".
If you move the mouse too far left... "save slot 4" will highlight... and you're back to it not working.
It's a PITA, but the workaround is to click halfway between slot 4 and slot 5, while you can still see the double triangle icon next to Yes.