Please try rebooting with "scsi_mod.use_blk_mq=Y" (I won't do that on your system). Since 4.20, device mapper uses only blk_mq. But our kernel still defaults to CONFIG_SCSI_MQ_DEFAULT = "N". This will cause all maps on top of SCSI devices to fail. This is likely a bug, but please let's confirm it by checking if the module parameter works.