Macbook Pro M4 Pro won’t connect to two external displays at the same time

I’ve recently bought a new monitor, and now want to connect my two monitors into my Macbook Pro M4 Pro, but the computer will only recognise one of the monitors at any time.

I’ve seen various reports of this online, but can’t find a solution. I’ve spoken to Apple about it, and went into the Genius store today.

I’m using the Thunderbolt connections. Monitors are MSI 4k.

I’ve tried:

• Different cables, including top-of-the-line TB cables
• Different monitors
• HDMI and TB (instead of two TB)
• Using a dock, and even connecting DP via the dock
• All the ‘simple’ solutions, including changing accessibility permissions, erasing all contents/settings to ensure there haven’t been any migration issues, safe mode, new user, etc.
• Lowering the refresh rates on the monitors (monitors are set to 1920 resolution)

To be clear, either monitor works fine and flawlessly if it’s the only one connected. I can have both connected, then take out the one that’s working and the other one will then come on.

I’ve also tried the monitors with my Intel Mac from 2018, and that works fine.