Aspire 5 A515-44-R3T5 Boot Mode - How to enable legacy boot in Bios

requiredusername

Hi, 
I have been setting up a few new laptops and have a problem with an Acer Aspire 5 A515-44-R3T5 with bios version 1.06
In the bios under option "boot mode" I can't select legacy, it shows up as an option but is greyed out, only UEFI is selectable. How can I enable it, I need it to set up various Linux distros that must be booted using non-uefi mode. I have made a bios password but that only let me disable another option, "secure boot".
The other new Laptops, a Lenovo and Asus (both with new Ryzen-5 4700U CPUs), allow legacy boot, it is not a hardware problem. I have around 14 days for an order of 98 of these laptops for work. If legacy boot can't be enabled they are useless for my job. Already contacted Lenovo support and they have replied, rather cryptically with  "legacy support is offered via CSM on the Aspire 5 series" ???.
Do I need a new bios, or is their a hidden way to enable this.

Thread edited to add model number to the title.

Jabroney

Has there ever been a follow up to this thread, I am in a similar situation needing Legacy mode for a specific use. I feel like it is safe to assume the Laptop is incapable of anything outside UEFI but a final answer would be wonderful.