Your memory card is formatted in exFAT. Sometimes iBasso DX120 writes some information on memory card. After that, the recording session remains open. The session are closed when you turn off the player. If you removed the memory card from the worked player, then the session remains open. Therefore, your computer cannot work normally with such a memory card. You needs to check the memory card on the computer, which will close the session and remove this error. To prevent this from happening, I format my memory cards in FAT32.