Well, after a few weeks of trying, I am giving up on getting LG’s 34" 5K2K monitor to work with my shiny M1 Max MBPro (32GB, 24 graphics core).
The MBPro just doesn’t work reliably with this monitor. I am uncertain if it is the MBPro or the monitor, but from what I have read online I suspect the Apple ARM processors are just not production ready for this type of monitor.
When I first got it, I plugged it into the TB3 port on the right side of the MBPro (where there is a single TB3 port), and oddly it was detected at a lower than full 5K resolution and in addition system information said there was a second monitor connected - which there was not.
I was able to get it working at full resolution by connecting to the other side of the MBPro, and for the past two weeks or so it has been working fine with the MBPro remaining docked and connected to it (via the OWC TB4 hub). Yesterday I also hooked up my older LG 27" 4K as a second external monitor and all was fine.
Today when I woke the MBPro from sleep, the 5K is detected at a lower res. In Displays preferences, asking for scaled resolutions (even with the option key held down) does not show the full 5K as being available. Multiple reboots with and without the monitor connected, plugging and unplugging, plugging in directly (without the hub in the connection path) - no luck.
Oddly, if I have the MBPro open and not in clamshell mode it seems to detect the 5K correctly, and if I have the MBPro in clamshell and connect BOTH the 4K and the 5K, both are detected correctly. The 4K works fine no matter how it is connected and how the MBPro is set up (clamshell or open).
I tried DisplayPort 1.2 and 1.4 as there were some comments online that it worked with 1.2 but not 1.4 (note I already had it at 1.2 when this whole thing started) and still it is so unreliable that I simply cannot work with it.
I suppose there may be an eventual fix for the MBPro (Apple apparently stated a fix would be out in December 2020 (not a typo on the year) but everything I read online indicates this is still in issue). There is an out called BetterDummy that supposed fixes this by creating a “dummy” display and mapping it to the real display, but I don’t want to have this much money (nearly 1200) invested in a monitor that may or may not work at any given time.
So, unfortunately, I have to commit to shipping it back tomorrow while still in the return window.
Sadly, there seems to be NO high res monitor out there that works properly with the M1 Max at this time, beyond the Apple ProDisplay XDR. Although I am eligible for educational pricing, this display with the VESA mount is still going to hit $5000+ after tax, and that just isn’t a justifiable expense for me. Even the rumored upcoming new Apple monitors are projected to come in at about 1/2 the cost of the XDR, and it’s hard to justify even $2500 at this point.
I would think Apple could really sell a lot of units if they could get a high-res (eg 5K) larger format (32-34") monitor onto the market that worked reliably with Apple silicon and came it at a consumer-affordable price.