I have a new BMC mountain bike in a tubeless 29" setup.
I have replaced stock Vittoria Barzo tires with a better rolling 29x2.1 Vittoria Mezcal (bought new online from Competitive Cyclist).
All was well, had like 100 miles on them, then didn't ride the bike for a few weeks and front tire lost all the air (probably didn't have enough sealant as the same happened with the other one - I'm not experienced with tubeless). I don't hang this bike on the wall, it just sat leaning against the wall. It sat like that for a couple more weeks before I decided to ride it again. I pumped the air into the tire and realized it was losing air fast. Upon inspection I saw that the tire has developed tiny cracks on the sidewall through which the air was leaving (see pic).
I thought it was a defective tire and replaced it with one of the Barzos the bike came with.
Rode it some more, after a few months of riding let it sit for a few weeks again as I was traveling.
Same thing happened with the other Mezcal tire - lost air gradually, sat without air for a few weeks and when I put pressure in, I discovered cracks too big for the sealant to seal, just like the first one. The contact between the tire and wheel was solid, no air was leaving there.
Am I missing something about tubeless tires? Can you not let the bike sit with deflated tires for a long time? Or did I just get unlucky with a pair of defective tires?