Grub boot menu shows only one lowlatency kernel entry

[Lassi]

DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=19.10
DISTRIB_CODENAME=eoan
DISTRIB_DESCRIPTION="Ubuntu 19.10"

ubuntustudio-default-settings:
  Installed: 0.73
  Candidate: 0.73
  Version table:

Expected:
After running 'sudo update-grub', all installed lowlatency kernel entries are shown in the boot menu.

Actual:
Only the latest lowlatency kernel entry is shown.

The issue seems to be due to 09_lowlatency helper script. It only adds the latest installed lowlatency kernel to the list. Enabling 10_linux helper instead, all kernels under /boot/ were listed (-generic kernels also).

For example, I have the following kernels installed:
vmlinuz-5.0.0-20-lowlatency
vmlinuz-5.3.0-45-lowlatency

And with the default configuration, only 5.3.0-45-lowlatency is listed during boot in Grub menu.