Maximum file size for placed images?

For years I've been able to place images up to 2GB (on-disk size) into Illustrator, but suddenly I can't. My max is now 1GB (actually slightly less).

I've tried all the different ways to save the image (which is larger than 2 GB when open in PS, but only 1.35GB on-disk): .tif (all the variants), .psd, Save a Copy, change the DPI (without resampling), placing via the menu command (which process the data then says it's generating pixels, and then nothing else happens), dragging onto the artboard (which goes through the same steps, but only loads a blank box indicating where the link is. And the little icon for the file in the links panel is blank-see attached image. No, its not in Outline view.), and even dragging a .psd directly onto the AI app icon (which opens the image, but shows an embedded link with a slightly different name, which I can't unembed, due to "not enough memory (RAM)"). 

My machine is an M1 Max MacBook Pro with 64GB of RAM, and a terabyte worth of free space on an external drive for a second scratch disk. AI is up to date, and I tried two versions of the previous releases (27.0 and 27.9.something).

I had a colleague try to place it for me on her machine and got all the same results.

Has something changed recently, or am I missing something here? Some setting I inadvertently clicked?

I've got massive files I need to deliver in CMYK for a print project, and it's a real problem if I can only place them if under 1GB! 

Thanks!