Challenges mounting a USB Drive on Mikrotik HAP

Okay, I've been beating my head against a problem for a few days now and I've finally reached the point where I'm going to ask the group for some help.

First some background. I have a couple of Mikrotik HAP AC Lite routers running AREDN and I'm trying to set them up to enable the USB port for USB flash drive storage. This is to increase storage for MeshChat as well as to store files needed by IP phones on their startup. My model for this has been the following post here on the AREDN forums (https://www.arednmesh.org/content/howto-meshchat-mikrotik-hap-using-extra-usb-storage-files) along with similar directions I found for the OpenWRT firmware (https://openwrt.org/docs/guide-user/storage/usb-drives-quickstart). 

I've gotten these steps to work for two of my nodes with the extra step of having to add a mount command to my /etc/rc.local file to execute on startup. However, for the other two nodes I cannot get the USB drive to mount on startup. Entering the command manually via telnet (mount /dev/sda1 /mnt/sda1) works fine, but again I'd like this to be done automatically at startup.

I've tried adding this task as a cron job at startup using crontab -e and making the following entry "@reboot mount /dev/sda1 /mnt/sda1" but no joy. 

Does anyone have any suggestions as to how I can get my node to run this simple command at startup? Something tells me I'm making a very novice mistake here but for the life of me I can't quite figure it out.

Thank you in advance for your feedback and Happy New Year!
​Tom, KI6GOA