亞馬遜幫助里有說造成unavailable balance的原因：
https://www.amazon.com/gp/help ... 18060
Common reasons for an unavailable balance are as follows:
?One or more A-to-z Guarantee claims are being processed against your account. Some claims may take up to 14 days or longer to resolve. Starting from the date a claim is filed, matching funds equal to the amount of the claim are held in your account until the claim is resolved.（賬號里有AZ Guarantee claim,等claim得到解決后，亞馬遜會解除這筆凍結的資金）
?One or more chargebacks have been filed by a buyer against your account, or Amazon has received chargebacks against your account within the last 30 days.（最近30天，有買家提交chargeback claim）
?Based on information available to Amazon, we reasonably conclude that your actions or performance may result in buyer disputes, chargebacks, or other claims against your sales transactions on Amazon.（根據賬號表現及交易情況，亞馬遜推斷買家可能會投訴）
?As a security measure, we may also reserve a portion of your balance while we conduct a review of your seller account if we observe an unexpected change in your sales or account activity.（為了安全起見，亞馬遜對賬號進行審核，如果產品銷售和賬號活動有異常，亞馬遜會預留一部分資金）

可能是你這單賣的是高價值產品、或者買家投訴它不是正品。如果還是找不到原因，就去問問賣家支持

之前我賬號也有過unavailable balance，原因是給時間讓買家確定訂單是否有誤："Money from your orders is reserved in your account until 7 days after the expected delivery date. This ensures the buyer has a chance to verify that everything went well with the order."