Hey Furley,
It's a known defect on the XMR 800. The shock actually breaks on the lower end, due to the increased tire size and limited shock travel. BRP recognizes this as a known defect (although it took some arguing with BRP rep and dealer to have them concede to the fact it's a known defect). There is also a secondary condition that is a direct result of the broken shock. You will notice the inneer cv boot rip due to the over-extended shock.
I have a 2015, and 3 other friends have the exact same bike. We have identified 2 failures over a weekend ride where we had a total of 3 broken front shocks, and 3 ripped cv boots. After some arguing, the dealer agreed to replace the front shocks and axles affected by the broken OEM shock with the Fox Podium shocks that are found on the 1000 XMR. SHOCKer....the 1000 has the same size tires as the 800 and the 1000 has the proper shocks. We have been unsuccessful arguing that the rears should be replaced as well, but so far we have shown no signs of wear or tear and neither the dealer or BRP have any known issues with the rear shocks.
I hope this helps, but contact your dealer and BRP to complain. Why would they put a short travel shock on an oversized "Mudder" tire that is prone to failure.