M1 MacBook Pro 5K monitor refresh rate reset from 60hz to 30hz after restart

M1 Max MBP connects to Caldigit TS4 dock via one of the thunderbolt 4 bus, external 5K monitor connects directly to TS4 via DP port (via DP to USD-C cable that supports up to 4k @120hz).

Normally, after some jiggling, I could set the monitor refresh rate to 60hz while Mac being on clamshell mode. Yet each time my Mac restarts (it's been randomly restarting itself lately...) the monitor refresh rate drops back to 30hz. Can't figure out how to stop this from happening every time...

Have tried:

• Using different thunderbolt ports on Mac
• Using different thunderbolt 4 ports on TS4
• Unplug/replug DP cable from monitor
• Using different cable

Nothing worked.

I can get it to 60hz is when:

• Mac is not in clamshell mode
• Monitor is not mirrored

And the only way to get 60hz in clamshell mode I could find is to

• Disconnect and reconnect the monitor a few times

... but then it will restart the Mac :(

Before Mac restarts (when I can it work normally)

After Mac restarts