We have several clients using the Rift-S in exhibitions. They are getting constant "Define play area" even if it's set up as static.
On my Q2 I can in developer option disable this so when cameras are 'lost' it uses the gyro, losing the 6-DoF tracking but still keeping the head rotation. As soon as cameras are seeing again, full tracking is enabled WITHOUT any notifications or need to re-calibrate.
We really need a fix for the Rift-S to replicate this as our client is struggeling using the hardware as-is.
For many uses the Rift-S is used completely stationary, so any guardian/play area is not needed at all.