Fibaro FGMS001 false tamper

I want to share a “finding” that I don’t explain but at least solved an issue I ran into.
I have a bunch of FGMS001 and they work pretty good.

Today, I added a rule to get some pushover notification on tamper events.
I then started getting spammed with “tamper” alarms whereas the sensor would be just still.
I realized the device was sending TAMPER alarms on motion !

My associations were:

I could only fix the issue going back to the standard associations:

Now motion is reported as such and does NOT report tamper.
And tamper is also reported as such on tampering but NOT on motion.

Don’t ask me why…