I've got the same iMac (but with i5) and had an issue last night where it wouldn't wake from sleep. The only way I could get it to start was holding the power button for around 10 seconds. Other than this it is working extremely well, possibly better than Monterey. One thing I did consider - I'm currently booting from a USB external SSD, and possibly there could be issues with the OS deep-sleeping this? Once Sonoma 14.1 is out I might wipe the whole lot and install onto the internal SDD and see if this helps.Does anyone have a problem with sleep?My iMac can't wake up.
iMac 5K late2015(i7 6700K+M395X)with OCLP 1.0.1 Sonoma