Got a text alert and an in-app SmartThings notification of a leak, but it was detected by a motion sensor? What the heck? I cleared the alert and have not made any changes. Alert shows in Smart Home Monitor history.
Maybe a bug in the latest firmware update?
Anyone else experience this?
There have been two or three reports of this in the last week or two. Definitely report it to support.
There have been a couple of “false positives” I’ve observed on my two hubs over the course of a couple of years. Infrequent, but annoying. One was a false ‘motion’ alert that set off SHM. The other, on the other hub, was a false ‘door open’ when it wasn’t. [Edit: the count is now three times.]
Here’s the details…
True example of YMMV 
Are you using a custom DTH for the motion sensor? Maybe it has water sensor as one of the capabilities and a false alarm triggered it.
That’s what I suspected the first time this was reported, but there have now been three separate reports from different people of motion sensors newly triggering a leak sensor alert from smart home monitor. And only from smart home monitor.
So I now suspect an SHM cloud issue. 
In any case, I would suggest that anyone who has this problem report it to support and let them look at it.
There might be rain in the cloud. Drip drip. Precautiones, Piso Mojado