That's why I asked about what exactly not see this pendrive. Because CellOS doesn't support exFAT, while e.g WMM does.
If partition table is MBR, and if filesystem on first partition in a table is FAT32, then XMB, recovery etc. will see the pendrive. They simply must. If not, it is hardware issue.
Also definition see/not see is not clear. Proper environment which w.g XMB will see, doesn't guarantee to list e.g in Photo category if user will not make folders on specific names. In such case, users often says: "it doesn't work" while it is enough to invoke context menu (by triangle? I forgot) and choose show all option. AND. Besides that, we have homebrew applications which not must use system stuff but their own like e.g WMM or IrisMAN and in those case, exFAT and NTFS will be recognized while e.g XMB will reject it.