Export from Sketch - vector to SVG strange output

I'm trying to export some vector icons I drew from sketch into SVG and PNG.

Here are my icons in sketch:

All nice and crisp. The shapes are in a group and against a mask, like so:

When I click export, I export them to SVG and PNG.

Here is the PNG's on a webpage:

These look great, exactly how I want them.

Here is the SVG's on a webpage:

The hexagons are no longer rounded, and at some points the stroke is thinner (eg - the bottom of the first icon) and some times it just completely disappears) also, the mouse cursor on the third icon has rotated to be facing straight up!

Does anyone know how I can make this export just like the PNG's but in SVG format? I can't seem to see any other option than 'export' so not sure what i'm doing wrong?