I finally did the 16.04 --> 18.04 --> 20.04 upgrade yesterday and now I don't seem to have hot swap capability. It worked perfectly before in 16.04. Yes, it's set to AHCI in the bios.
lshw lists
RAID bus controller
product: 631xESB/632xESB SATA RAID Controller
vendor: Intel Corporation
physical id: 1f.2
bus info: pci@0000:00:1f.2
version: 09
width: 32 bits
clock: 66MHz
capabilities: raid pm bus_master cap_list
configuration: driver=ahci latency=0
resources: irq:19 ioport:20e0(size=8) ioport:20f8(size=4) ioport:20e8(size=8) ioport:20fc(size=4) ioport:2080(size=32) memory:f0204400-f02047ff
Any ideas?