BTW, I finally got around to copying a moderate size MP4 file (61 MB) onto the eMMC C: drive, then cutting and pasting that file to the SATA M.2 drive, then opening the file (viewed with Windows Media Player) from the M.2 drive — which worked just fine.
Did some research. Apparently that N22 may be twitchy about what m.2 drives it will work with. The BIOS limits the maximum m.2 drive size to 256gb. Their forums and documentation also list only these drives as being compatible:
128GB LiteonCV3-8D128 M.2 part number 2280128G
128GB Samsung PM871a
5SD0J21066 Liteon CV1-8B128
5SD0H43484 HY HFS128G39MND-3310A M.2
5SD0L07408 Hynix HFS128G39TND-N210A
5SD0H00094 Samsung MZNLN128HCGR M.2
16200609 SS MZNTE128HMGR 128G
5SD0H29265 HY HFS128G38MNB-2200A M.2
5SD0H12051 Ramaxel RTHMB128VBM4EWDL
5SD0L14643 SS MZNTY128HDHP-000L2 128G
5SD0F65755 Liteon L8T-128L9G 128GB M.2
16200483 Liteon LGT-128M6G M.2
16200587 Samsung MZNTD128HAGM 128G
5SD0M61137 Ramxel S121 128GB M.2 2280 SSD
5SD0L82503 RTITF128PCA1MADL 128G M.2 SSD