It is possible that your exchange is not in compliance with the regulations. Fund companies have the requirements of minimum redemption share and minimum reserved share. If it does not meet the requirements, it is not a valid redemption.

For example, if you have 1 100, and the fund company stipulates the minimum redemption 1000 and the minimum retention 1000, you can only choose to redeem all 1 100, and any other application is invalid.