It sounds like the Greek characters are missing from the font the Android app uses. I’ll take a look at that for the next update, but until then you could try switching to one of the other map styles perhaps (using the button in the top right) - Wayfarer is the same information but with different colours and fonts, and then the various third party maps should work. 

Brilliant thank you that has resolved my issue!

Chris, I'd be interested to know how you find cycling in Greece. We're thinking of heading there maybe October, Athens from Skopje. 

Thanks, Rob

We actually won't get there until the end of September/ start of October either as we're currently in Slovenia. We're sat around waiting for a new wheel so getting ahead on the route planning