Yes, it's just that lithium AAs have too high a voltage initially. I just measured some at 1.8v, despite them being rated for 1.5v. That's too high for the GPS.
Using them in a D10 torch for 3 minutes on high each dropped the voltage to 1.5v, which my GPS60cx would accept. 3 minutes is roughly 5% of how long they should last in that torch. I have known the batteries to recover their voltage after a while, so although I try to keep a set of pre-used ones for emergencies, I wouldn't be too surprised if I had to repeat the procedure when I came to use them.
It's definitely something worth knowing about in advance, if you plan to use lithiums in the field.
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