CommentStreams:87f6766e851787f80d8226775560dc2d

I found a solution and I am updating my original post.

Thanks to an article at www.root.cz/zpravicky/#zpravicka-9 and a subsequent discussion on the RPi forum at forums.raspberrypi.com/viewtopic.php?t=394580&sid=5cdec88004c1bedee4b2a8fb34b4e510&start=125#p2375717 regarding the Radxa controller (which uses the same JMB585 controller), I followed the instructions and added the line dtoverlay=pcie-32bit-dma-pi5 to /boot/firmware/config.txt. Everything is now working under the 6.18.x kernel branch.