Please see the following links for the approved SD cards and Format Utility.
SD Cards for Multi tracking: https://support.presonus.com/hc/en-us/articles/115000921126-Recommended-SDHC-Cards-for-Multi-track-Recording
Approved SD Card: https://support.presonus.com/hc/en-us/articles/115000219906-Which-SDHC-Card-should-be-used-with-SL-Series-III-Consoles-
SD Card Format Tool: https://support.presonus.com/hc/en-us/articles/115000236783-What-utility-should-I-use-to-format-my-SD-Card-
I also don't understand this "best answer" when yu say that you have done everything as written, so log a ticket and ask Support....!
By the way, Supoort asks what the size/capacity of your card is. ;-)