App misbehaving on ForeRunner 935. Fine on simulator

Hi,

I have a watch app which works fine on a couple of watches, but on a 935 it misbehaves.  It's mean to draw lines on the screen, which are downloaded as a json file. This constitutes a map.

It works in the simulator, but on the watch the screen is blank and having got some debug logs off the watch itself, I get a strange output and hoped someone might be able to shed some light.

Each json file has an ID which is a string. This string is number/number/number (eg. 32754/25849/17) respresenting a map tile location

I print the current tiles which are being displayed. The code to populate the tile ids is:

var tiles = new [totalTilesX * totalTilesY];

var x = topLeftTileX;
var i = 0;
while(x <= bottomRightTileX){
var y = topLeftTileY;
while(y <= bottomRightTileY){
tiles[i]= x + "/" + y + "/" + z;
i++;
y++;
}
x++;
}

return tiles;

Then, later on, the code to print the ids

System.println(tiles);

On the 935 Simulator, and on my watch (vivoactive) and a fenix it prints the strings when I print the array.

[32739/25972/17, 32739/25973/17, 32739/25974/17, 32740/25972/17, 32740/25973/17, 32740/25974/17]

On the watch where it doesn't work, when I print the array of values, it prints

[f.a.q.b.l@92a741b2, f.a.q.b.l@92a7b611, f.a.q.b.l@92b1b63b, f.a.q.b.l@86f0b2d1, f.a.q.b.l@86f12730, f.a.q.b.l@86fb275a, f.a.q.b.l@7b3a23f0, f.a.q.b.l@7b3a984f,