Perhaps not a bug, but might save someone else some frustration.
I’m using a brand new SanDisk microSD card (Extreme Pro 128GB) with my S2400 (20210812 firmware). The MicroSD to SD adaptor that came with the card worked fine in my laptop (formatting and then copying samples) but the S2400 refused to recognise it. Not shown in the file browser, “Format” option gave “Error 12”. Removed and inserted several times (and confirmed still working in my laptop), and double-checked the write-protect tab wasn’t engaged.
Later I switched to another card adapter (a non-SanDisk generic) and it’s been working happily since (in both my laptop and the S2400).