OHR cracks

I haven't.  What is the white corrosion in the circle surrounding the oHRM?  Maybe this is what's causing the cracks in the resin covering. 

I’ve not see anything like that either. On a grim note I think the white stuff is sweat and skin...I hope it is anyways. 

Think it's sweat, it is not corrosion. 

I've had a 935 for years and my 945 since the first week of May. I wear them 24/7 except for charging and I haven't had any cracks. The OP is experiencing this for the 3rd time. It's possible it's a case of bad luck, but I wonder if it's maybe a soap, shampoo, or lotion they use that might be reacting to it?  Hand sanitizers contain a lot of alcohol. Maybe something like that? 

I swam/swim a lot in chlorinated indoor pools here in the UK. I don't wear any lotion nor do I use hand sanitizers. I do wear the watch in the shower, but it always gets clean, fresh water over it at the end of my shower.

I'm not sure then. It's possible it could be a pool chemical. I had a pool and a hot tub and chlorine isn't the only chemical present.  This was prior to owning those watches and I rarely pool swim myself. There have been several reports of cracks on watches. Any of them mention pool swimming?  

It would be awesome that a watch made for swimming in the pool couldn´t resist chlorine.

I was about to reply that I have an even earlier version and no issues....... but when I went to look, I have a huge crack right through the middle that I swear wasn't there a few weeks ago and a couple smaller ones showing up now too. Oddly enough I do lots of pool swimming but not in the last few months. Once the weather warms up enough I do most of my swimming outside and have not spent much time in the pool for the last 4 months or so. My serial number is in the 5Z6002XXX range.

That's disappointing.  I had a conversation with kitenski and I thought it may have something to do with different manufacturing products from different parts of the world. (IE, resins, glues, etc).  If I remember correctly, we're both from the Pacific Northwest and that blows my theory out of the water.  

Yeah, I'm in Oregon and my watch was a direct purchase from Garmin. All the watches are manufactured in the same factories in Taiwan though so it isn't a manufacturing region thing. Maybe a regional environmental thing, but it seems to be pretty broadly spread out from what I've seen on this forum. I have had this issue before on a Fenix 3HR but not on the FR935, Fenix 5, or Fenix 5+ that I have had since then. I got my FR945 on May 2nd, so it has shown up as a problem within the first 6 months of ownership. The crack on mine is MUCH bigger and in a worse spot than the one kitenski's watch has. It is directly over one of the black sensor squares and all the way across it.