MX Linux: Grub boot taking way long time

I noticed that GRUB gets stuck and tries to load attached external usb hard drive instead of the internal HDD. If I remove external HDD during boot then it loads immediately. Is there a way I can stop GRUB to look at attached external HDD, atleast until it's loaded linux completely. Attached external HDD has media files & is not bootable but it has few tera bytes of data. I use the machine as plex server & need the external HDD attached if system is rebooted. In the GRUB logs I see it gets stuck at this point - Using makefile-style concurrent boot in runlevel S. Starting hotplugevents dispatcher: systemd-udevd. Synthesizing the initial hotplus events (subsystems)... done. Synthesizing the initial hotplug events (devices)...done. Waiting for /dev to be fully populated...done. Any suggestions? Linux version Is MX-21_x64, kernel 5.10.0-11