After weeks of having this problem, I found that it only occurs when one account is signed in and a second user logs on. Restarting works because it signs out of all accounts. I also found that I can use task manager to sign other users out, which immediately un-freezes the taskbar. But only administrator accounts can do this, so restarting the PC is the only workaround for the kids' accounts.
The problem only happens when the razer turret is connected to the PC, either wired or using the wireless dongle. Having synapse installed or not didn't make a difference. I have completely reinstalled windows and installed the turret first, and the problem still happened. Finally I did make sure I have the latest firmware, updates, etc.
Anyone else have this issue? I saw one similar post from 2018, but it's for another product, has no replies and is locked. A fix would be great. I would really like to use the turret for PC gaming on the big screen TV from my couch, but it's too much hassle to get stuck at log on and then have to restart the PC.