CD-ROM drive fails to open/recognize inserted cd in Legacy boot mode

Recently I wanted to check that I'm able to read cd/dvd disks. No my surprise my "old" laptop failed to do so. After investigating today I've found out cd drive works on Linux Mint 17.x booted in both legacy and UEFI modes and for Linux Mint 20 it works only if booted in UEFI mode. In Legacy mode LM 20 first terminal command eject sr0 took a long time, drive had not opened, next time it returned immediately w/out any visible effect. journalctl shows nothing at that time, overall near the end ata2.00: revalidation failed. If drive is open with external button, inserted cd disk is not shown in disks GUI (no media, CD/DVD drive itself is shown as /dev/sr0). Why is there a difference how I boot the distro? Where/what to investigate further? I'd like to understand and fix the issue. TIA